I'd like to see more diplomacy options, as well as a retouch on current ones.
In last game I won diplomacy victory. I had a power of ~250, while other 4 empires had 120, 70, 50, 30.
We had an event that forced all players to war. After couple seasons bottom factions offered peace to me. 120 one took about 30 seasons - they did not even want to talk meanwhile. They were still at war between eachother.
And here's the thing, as soon as I researched alliances, I could ally on same turn with EVERY faction. Why would X ally with me when I am an ally of Y, and X and Y are at war? Makes no sense.
There is no option to trade / demand a city. There is no option to demand an AI to make peace with one of your friends / allies. You can't offer troops to support an ally.