Improved Culture
you know, one of the concepts that i love the most is culture, and all the things that it can do for you. but i have some ideas that might make it even better....
1. culture should affect your allies, if an ally's planets are bathed in your culture, they should get some resistance, but not much; they should be able to lose their planets like anyone else
2. perhaps for the Advent, once you research something (tier 6 maybe), instead of rendering a planet neutral because of culture, they should auto-join you (so you dont have to go and colonize it)
3. if you do neutralize a planet because of culture, all of the orbital structures should be demolished as well (they are rebelling after all!). i just hate neutralizing a planet, then i have to go and destroy all of the structures surrounding it!