Ric,
I think the biggest difference between my strategy and others is that I'm unafraid of fighting an AI. I'll take one on early in the game if there's two other AIs also at war with them. The AI is so bad at attacking, that even with a military disadvantage it is not too hard to out manuveur them (though I had a LOT of practice at the lower difficulties - I can look at a map and pretty much tell you how the AI will respond to an attack.) For example, if the AI is at war with a major that is closer to it's terriority you're unlikely to ever see a transport... assuming you have ANY ship (even a freighter) on each system you own.
I only ever culture bombing one or two majors because I've invaded the rest. I don't believe in alliances unless I'm clearly going to lose without one... I've also never culture bombed an ally.
I'll have taken a large number of planets using my gang up on the weakest major strategy -- and conquer any remaining minors before starting the culture bombing. By the time I take out the majors and minors, they've build capitals and hyperion centers and my production is really high (also I've inherited a large number of phantom trade routes from taking systems.)
Combine a planet advantage with nearly every maxed out resource, and I'm typically ahead at that point in the game in everything except perhaps military / manufactoring. But I'm always close behind there and I'm WAY ahead in Tech, Economy, and Influence. At that point, they don't bother threatening me at all.
I suspect that influence has a BIG impact on relations / what the AI will put up with. I always demand IP on tech trades and I constantly trade techs so I end up with a massive advantage there. (A major can have an influence resource and a similiar number of planets and I'll still lead in influence.)
In terms of military, I trade tech for capital ships. Dreadnought seem expecially cheap in the later game - so my military rating is respectable - in fact, due to owning the military resources I can take out Avatars and Rangers with by Dreads if I need to. If I have to, I'll lease an Overlord or Excalibur from Mitrosoft knowing that the game won't last long enough for it to hurt me.
The two times this has started to backfire, I've sued for peace by 'giving' the major a planet in the heart of my empire knowing full well that I'd culture flip it within 6 months.
I'm curious to see if anyone else uses a similiar aggresive strategy. I also tend to play smaller maps (though on common or abundant) so there is more of a tactical element to my games. Larger maps are harder for me, because while I know where the AI is sending ships I can't always react in time to exploit this knowledge.
-Cypher