Since there is a possibility of Embassy ships, they are a couple small changes I love to see.
The AI respect its government/race traits, eg pacifist reluctant to go to war.
An AI that is honourable if they wish to go to war make a declaration that does not start the conflict until after a number of days, to give a chance for embassy ships to escape.
The AI respect a claimed system and not build colonies
A rumour mill that pops up in logs every time there is a status change, perhaps to save you some work we can all post a sentence or 20, for different levels of how the AI views your population.