I've always found the idea of all of these terrible only because I am not really assured there will be more than one team playing, interacting with each other is all fine and well, but the Civ AI is stupendously horrible and MUST be replaced with other human beings for this to be any fun for me,
It would be interesting to see how this could work if we dropped a pyramid in everyones capital and let each civ pick their own ruling system, of course we might be wary of trying to change governments that might exclude players unless they want to leave.
One question i have is how do you guys deal with happiness and reform in this game? Unlike many others, Civ is a game of few repercussions, and there isn't much to be afraid of as far as unhappy citizens and decisions on what to build often seem fairly straightforward with every citizen being silent in the matter