o Add an option to liberate cities. If you liberate an Ally's city, have the option to return it to them for free and a big influence / relations bonus, or keep it for a big relations hit.
Yes! This would be great & make alliance victories more fun to play for.
Under Good, I really like how scarcity effects how the AI values resources - if you have lots of crystal and your opponent doesn't, there's some serious money to be made.
Also, Capitar's ability to generate influence through trade routes makes Silver Tongue much more powerful in the early game than for Kraxis - I have posted elsewhere about getting Knights of Asok way early using Legacy of Serrane plus Silver Tongue. A nice trick for the merchants! Presumably a custom Altar sovereign, if they can get enough quests, could use it better still... A nice hidden bonus for diplomatic players.
Under Bad or Bugged, I would add some odd stuff I've seen in .915:
A powerful Capitar trying to bully me into paying tribute (and paying more gilder than I had for the privilege). When I refused, they immediately declared war... fair enough. When I closed that dialogue box, a third popped up asking me for an economic treaty, with our faction relationship already showing WAR in big red letters. While I approve of the chutzpah I assume that this is a bug.
While generally lots of contact with the AI is a good thing, in a different game I had three turns in a row of Altar asking me for 35 civ research in exchange for 35 civ research. Unlike the above this seems to be eccentricity rather than obviously bugged.
In my games as Krax or with my diplomatically-inclined Capitar sovereign, I don't see any actual benefit in my trades from diplomacy - they're no more valuable than when I play as warmongerers like Yithril or Umber.
How influence is generated (apart from quest rewards, questing as Altarians, or finding prestigious locations) isn't entirely clear to me, and if there's a hiergamenon entry for it I can't find it.
Tribute seems to be bugged when AIs offer it - the text offers tribute but the actual treaty on offer is a demand. Don't have a screenshot handy but I think there have been posts about this elsewhere.
Peace treaties (AI loses war) are harder to negotiate than surrenders (AI loses game) - the AI needs a big bribe to make peace but can be intimidated into surrendering relatively easily. This seems wrong, to put it mildly.
The first two are one-offs for me but the others have come up in multiple games and/or been mentioned elsewhere on the forum.
Under Good But Probably Bugged, I have seen warmongering AI break non-aggression pacts a couple of times, in one case only a few turns later. I didn't figure out if this happened because of a decline in relations expiring the pact early (which I guess would be a cool feature) or if it was just a bug, but since it led me to a ) gasp with shock and b ) legitimately use the phrase "curse your sudden but inevitable betrayal" (if only to my computer) I was cool with it.
(Edited for sudden but inevitable emoticons)