Hello All:
I didn't think it was fair that the at-war diplomacy penalty was so much greater than the at-peace diplomacy bonus. Rather than decreasing the at-war attitude, I decided instead to increase the at-peace bonus. This made more sense to me, but also, the at-peace code is easier to decipher.
In my mod, peace gives a greater diplomacy bonus - instead of "Years of Peace have strengthened our relations +1" - you get up to +4:
max +4 for peaceful civs (<iBasePeaceWeight> 9+)
max +3 for rational civs (<iBasePeaceWeight> 6-8)
max +2 for irritable civs (<iBasePeaceWeight> 3-5)
max +1 for aggressive civs (<iBasePeaceWeight> 0-2) (no change)
To accomplish this, I adjusted the <iAtPeaceAttitudeChangeLimit> values to reflect the max peace bonuses listed above. The <iAtPeaceAttitudeDivisor> is the # of turns for at peace attitude incremement change of +1 (60 turns - all leaders).
I think this is more fair, as "you declared war on us" has a max of -5.
The only problem I found - the +1 per 60 turns starts at the very beginning of the game (4000 BC), before you've met anybody, rather than at the point of first contact with each civ. I couldn't figure out how to modify this, but overall I'm very happy with the in-game performance. (Note: I'm still testing incremental attitude improvement in post-war relations recovery. I keep forgetting in-game that I need to go to war with someone other than an aggressive civ for testing purposes.)
Regarding the <iAtWarAttitudeDivisor> and <iAtWarAttitudeChangeLimit>, I couldn't figure out why there would be a negative turn value instead of a negative attitude change limit. You start at the max value (-5), and I don't think it becomes any more negative over time. Also, I couldn't figure out which variable was for "This war has spoiled our relationship." So... in short, I sort of abandoned trying to decipher the war variables. (I like peace better anyway,

)
Anyway, that's what I've figured out. I'm sorry it's not directly on topic, but I hope it helps.
-Laina