Somehow didn't see this post until now...
Yeah, it can get annoying when the AI has carelessly built up [strike]my future[/strike] their planets.
Some of the rules that have been set make little sense to me; for example, why would only one race be able to produce a trade good? For that matter, if I give another race my trade good -- which symbolically, I think, is meant to suggest the right to produce that trade good for themselves -- why do they not have to spend a tile for it? They're certainly not using my tile. Compare to China producing knock-offs of popular American products. But maybe I am misunderstanding the nature of trade goods, however.
I also don't really understand why it is that, if my empire can only build one economic capital, it is perfectly capable of absorbing someone else's. This implies to me that it should be possible to build a second there, without having to conquer it, if I had reached that planet first. It would make more sense if the econo-cap limitation was based on physical geography, ie. distance from each other, rather than political boundaries. What I mean is that there must be a certain amount of space between your one economic capital and your second, third, etc. This would also give a new dimension to the economics of games played on huge maps.
All that said, I try not to worry too much about how "logical" game mechanics are. It's easy to drive oneself mad trying to make a game conform to realism, especially a science fiction based game. When I sit down to play a game of Chess, which I do a lot, I don't think in terms of its realism ("Why can the knight only move in this pattern? Is his horse lame or something?") but in the abstract. With a more realistic game like GalCiv2, or less abstract I should say, this is more difficult to do I suppose.
Got a bit sidetracked there, sorry.
Also, GW, would you mind emailing me the code for our banner? I seem to have lost the instructions on how to do it. Thanks in advance.