I think there's a fair bit of support for the buildings modified by population idea, but if that's going to happen then we need clarification:

Will the removing of the wheel mean a significant reworking of the fundamentals of the economy or not?

Presently, the economy calculation is population+modifiers=production, production*setting +modifiers = manufacturing, and manufacturing * slider + modifiers = military manufacturing. If this equation is to remain in the game as the foundation of the economy, then the building concept doesn't apply to the discussion. 

So, is the wheel's replacement just going to be a UI change, or is it going to be an outright change in how we create manufacturing/research/wealth? Because I think what most of us fear is a UI change that takes away our ability to interact with the production equation without altering that equation itself in any way. 

Not at all. Because on larger maps, the choices at the start have serious consequences ... but after the expansion the single planet is one among many, meaning the choices for it have far less consequences on the big picture. Instead, the big picture is influenced by the sum of all choices for those many planets.

It's like McDonalds. McDonalds started with a single restaurant and expanded to a cooperation with thousands of restaurants. Obviously the management decisions for the first few restaurants had far more gravity - because if the first one failed, the expansion would have never happened. Today the single McDonalds restaurant is only a small part of a big apparatus, if it fails it doesn't mean much. Today only the sum of all the thousands of restaurants counts. That means the managers at top need to employ completely different tools and strategies as the managers of the first, single McDonalds. It would be insane for the top managers of McDonalds today, to try to manage each restaurant as if it were the only one. The opposite is also true, in the beginning, the managers of the first McDonalds would never have achieved any succes if they had tried to manage a single restaurant like it was a world wide cooperation.

GalCiv needs to learn from McDonalds and give the player the tools to act like a single restaurant owner at the start and develop into the top manager of a huge coorperation.

Well, tbh I don't really micro much at all.

I colonize the planet, fill up the queue, set it to 100% manufacturing, and then wait. When the planet's done building and alerts me, I switch it to 100% whatever it's supposed to do. Then I ignore it forever after.

Now, obviously this means no upgrades, but I mod in a change of bonus 5 production from colony capitals to a flat +5 social manufacturing bonus. This 5 social manufacturing is now unaffected by the wheel and always applies. This gives my research and econ worlds a small but constant manu income that can be spent on upgrades. 

This way, I have basically zero micro beyond initial planetary setup and the population changeover. On some planets, I don't even bother with 100% manu initially - I just set it to 100% on whatever it's eventually going to use and let it build from the 5 social manufacturing. Every research or econ planet becomes fire-and-forget; I organize it on day 1 and then never, ever return. 

And that's from a very minor balance change on 1 building. It also immediately and massively nerfs colony spam, because you don't get the equivalent of 5 free population from every planet anymore. One of the things that makes the player so OP early on using the wheel is that 60% or more of his Raw Production might be coming from the colony capitals.

This is why I don't think the wheel has to go. The economy is hopelessly unbalanced presently in more or less every field; players are achieving insane output levels because they're being given insane bonuses to multiply against each other. Give them reasonable bonuses to play with, and they'll produce reasonable output.

I generally find that the economy goes delinquent somewhere around Tier 3 in the buildings. That's when the player starts to achieve takeoff, and starts outpacing the AI at a geometric rate. This strongly suggests that the fundamentals are fine, since it's working OK prior to T3; it's only then that I start producing Huge hulls with the latest kit on them in 1 turn from every shipyard supported by 1 industrial planet. And the logical place to look for the solution is reducing the bonuses that the player begins to pick up from T3 onwards - the point where the impact of building upgrades begins to accelerate. Kill that acceleration, reduce the bonus offered to 5% or 10% per tier full stop, and you've reduced the mid-to-late game overproduction problem enormously immediately without having to change the production mechanics.

Oh, and for God's sake, nerf adjacency bonuses into the ground. They're ridiculous. 5% per level is too high. It leaves you with limited granular control over the bonuses being contributed by building levels. Set adjacency to 1% per level for everything, and then adjust the levels offered by buildings. This would allow you to use a whole wonderful variety of numbers - still want solar planets to give 10% extra output for each factory they're next to? Give it +10 manu level bonus. Low-adjacency buildings (like the staple factory, research lab etc) should be giving out just 1 or 2% bonus for adjacency, otherwise we end up with the silly situation of putting a factory between 6 other factories being worth more than the factory itself.Adjacency should 'sweeten the pot' - it should allow the micromanager to get maybe an extra 10%-15% total output over the guy who just plps improvements down willy-nilly. At the moment, a well-planned planet might get half it's output from adjacency increases.

I like to build up tall and micromanage my core worlds, and keep on micromanaging them. It's part of enjoying the game and because the core worlds are only a handful it's not that much. The rest end up being "generic research worlds" or "generic manufacturing worlds" or whatever I happen to need when I get the world without much thought to fully maximize them. The main reason for this is, of course, that there are just so many planets in your empire that you lose interest in micromanaging them all. However, I do like to micromanage the handful of worlds I deem "important" as that's both manageable and fun, and would sorely miss it if they removed the possibility to do so. Economy building is just as much of this game as warring.

The game should allow the player his freedom to build planets to his taste and allow him the success of creating beautifully working economic engines. It should also support him in doing so by making it less about manual continuous steering and instead be more about making choices.

I want the illusion of being in total control and being limited by nothing except my imagination. The intended limits in the game should come from a "gentle seduction" approach where optimal choices naturally steer me towards acting like I'm "supposed" to be acting. If this makes sense...

If the "buildings=output" is too much in work and cost, then re-balancing the game so that the cumulative result of the bonuses doesn't get to ridiculous levels would be a good way to fix the problems. Also, the micromanagement issue could then be solved with the governors but not with the current approach. Instead the governors should really be designed as automatic optimizers that go on and maximize the desired chosen output i.e. exactly what the players do with micromanagement. Let the player setup the build queue and make the governor care only about the eco wheel and slider. Then the output optimization reduces to a simple and straightforward process. Such a governor would then be directly useful for the AI, too, as it needs only to come up with suitable build queues and then hand it over to the governor resulting in a tremendously more powerful AI opponent.

But yeah, think about the "buildings=output" solution, too. It's simple and works and would render the eco wheel unnecessary in a quite natural way while leaving the player free to tinker with his planets. We do understand if you say it's too radical a change and would require major overhaul of the internals and cost too much. But who knows, maybe it wouldn't?

It would very much surprise me if they remade the entire economy model as many here have suggested. At best it would be in an expansion, and the reason for changing it would have to be very good.

Excellent! Your getting rid of the planet spending wheel. I suggested doing that when you were in beta. Will their be an empire wide spending wheel?

What to do in place of it? Please don't add things that you can't also have the AI do an excellent job at.

Have an option to remove the ability for the player to directly build on planets. This option would only allow planetary governor use. I'd expect to be able to out manage the planetary governors. Give me the option to level the playing field against the AI in this area. I choose a governor. He does his thing on the planet. I can only choose a different governor to change things.

A major issue I find with game/AI balance is that even early on, it becomes possible to have ships with 20+ moves.  In the later stages, you can have ships with several hundred moves.  This makes in virtually impossible to build any sort of defensive line - if you put your forces in a forward position, high speed transports can run right past them and conquer all worlds that are anywhere near the front line in the first turn.  If you spread your forces out to defend your planets, then a concentrated high-speed enemy fleet can defeat them in detail, allowing the high speed transports to once again conquer all those planets in the same turn.

Thus, in a PvP war, whoever attacks first is likely to gain a major advantage before their opponent even gets to move.  In a player vs. AI war, the player can easily bypass any AI defensive measures because the AI has no hope of dealing with 20+ move ships.

Right now, miltary starbases do have modules that impede movement, but you need to have several off them to really affect high-speed ships, and with the limited area-of-effect, it's prohibitively expensive to build the kind of wall you'd need to meaningfully impede enemy movement.

So, in order to make a difference, military starbases would need a considerable AoE boost (at least +4), and the strength of their movement-limiting powers would need a considerable boost as well.  In addition, the AI would need to learn how to build a continuous barrier of them against anyone nearby who's building transports - otherwise, they would be hopelessly easy to conquer.

That could work too.  It would definitely be easier for the AI than having to build a line of military starbases.

I would like to second this:

If you are going for something different and the theme is going to be "less micromanagement", how about turning the buildings vs. population the other way round?
In the current system you have a population that produces "generic work" that is then split with the eco wheel and then these are affected by the bonuses from the buildings. The need for the eco wheel comes from the basic setup that you have a population generating the base points. What if it wasn't?
Alternative idea: make the buildings output directly manufacturing, science and money and have the population affect that output. Define how much population a single building of a given type needs to function at "normal" level and then penalize the output it if you have more buildings than population to run them, and perhaps some kind of diminishing returns if you have more pop than buildings that can use them, or even turn the over-population into "generic workers" that produce some small amount of manufacturing. The adjacency bonuses can stay, won't harm the concept.
The result of this is that now you have no need for the eco wheel at all!. The specialization of the planet is entirely determined by the buildings on it. What's more, the population growth imposes a limit on how fast you actually should build improvements as empty buildings won't give you much until you have the population to run them.
From the point-of-view of having fun, this gives the player the freedom to specialize his planet to however he likes but he doesn't need to do anything else than think which improvements he should build. From the AI point-of-view its specialization task got lot less hard. All it now needs is to determine a build-queue and manage it with some awareness to the population level and that's it. Player happy and AI competitive and lots of micromanagement cleared away.

I focus only on the question about the wheel.

I like the idea that the direct output is from the specific improvement, that is then modified by the population input to that structure. Gov's could then add bonuses and penalties to the three (production/Science/Money). Further....several things that Naselus pointed out are true as well. Empire wide bonuses have to be nerf'd or cut out all together. If you changed to the above system, then +'s or -'s for underpopulation/growth and overpopulation. This way...improvements would be needed FOR the population, providing some realism. You could go so far as to add some malevolent points for not producing new improvements before the overpopulation reaches a certain "trigger point"....percentage, ect.. or some pragmatic points for producing...say factories for the overpop, or benevolent points for a hospital during overpop.

The economy is a really fun and crucial part of GalCivIII, and some hard choices must be built in for the player.

Addendum: I also second the idea to cut out the large empire morale penalty, or at least add a monetary cost to upkeep each colony. There should also be an extra cost associated with governors. If morale dips too low for too long, there should be some kind of rebellion mechanic, where they would declare independence, or swear fealty to the next largest cultural influence in that sector.

Even still....I love this game. I hope this helps.       

Regarding AI: Please consider the scenario where the player concentrates largely on research, outpacing other CIVs in all other areas -this is enhanced by the exponential growth rate and partially by the production wheel but will not go away with the resolution of these aspects.

The AI needs a way to counter research berserk of the player with trade embargo ("You would like to have more tech Emperor Einstein to add to your glass tower eh?") by CIVs that are not overly intimate with the player. They should also concentrate more on their own research but better yet include military tech in your military rating and declare preventing wars when they notice you are outpacing them in the labs. Targeting research relics and research hub worlds in such cases is also a good idea to force tech development to a halt.

Until fleets get buffs (experience and commanders) and thus a couple of outdated ships perform better then a state-of-the art battlestar, research is a way to beat any AI without even paying much attention to ship config. The AI is good and getting ever better in fleet config, try to make this count a bit more then the naked tech level of the CIVs so a tech leading empire cannot cream all others with a few vessels. Combine this with the AI using more then one weapon types and support and the battles get exciting as the outcome will not be obvious

Wow planet wheel going away, I might actually start playing again. Good call Stardock.

  Honestly, it seems that the wheel is there just to be there. You could remove it while leaving everything else as-is.

  Every unit of population generates 1 each of manufacturing, research, wealth, and influence; specific buildings like factories and banks increase the total in that area just as they do now. Sure, the specific buildings might need to have their modifiers rebalanced a bit, but as someone pointed out earlier, that probably ought to be done anyway. The only difference is that you no longer have a redundant wheel (which inevitably just gets set to one of the three points anyway) to extra-super-duper confirm that yes, the factory covered planet should actually be manufacturing stuff.

i have been harping about this for ages, so i wholeheartedly agree with this change. i would put nothing in it's place. specializing planets via infrastructure choices is enough (i.e. what buildings are constructed). whatever you put in it's place please don't make on a per planet basis.