I'd love to hear about all of those. Especially a representational dictatorship...whenever the old dictator dies, the people elect a new one, who is to serve for life with authoritarian power. That would be so cool. From a literary perspective, I mean. Maybe not for real life.
Bizarrely, I was thinking of making my in-game government like this. It would certainly be an interesting idea, but since you've thought of it too I might have to develop a different governmental form

wuuuut...?
So AIs are useless in multiplayer? Or is it just that they refuse to communicate? We might want to add an AI to give the world a bit more depth, it's a Huge map, so ten people might seem to have too much space.
What do you guys think? Should I add an AI or two (perhaps on a lower difficulty?)? Even if some communication may be restricted?
CPM, may you explain more of the AI restrictions?
AIs are...weird in multiplayer. Essentially, unlike in singleplayer, AIs can't approach a human player with a trade deal, be it a "peaceful" one (Luxury exchange, e.g.) or a hostile one (DoW). Though I'm not 100% sure why, I think it's just due to lazy programming on the part of the Civ developers. Anyway, this means they just sit around, building big armies, and spamming wonders. This in turn makes them really, really dull and also pretty aggravating.
I'm not completely averse to having an AI or two in the game, but they might end up being more annoying than we want. To fill the extra space, perhaps we instead add in a few extra City-States? (Yes, even though we have a Venice in the game!) Alternatively, we can just leave the space open and have to deal with more barbs.