Hey,
since you intend to listen to some of your fans ideas, here are some of mine concerning diplomacy. Since I prefer to combine all methods in order to win (alliances, influence and military) I would really love to have changes in the diplomacy area more than anything else....
1. Treaties:
Non Agression Pacts - you know them, we need them. Allow us to limit them (1 year, 2 years)
Tech-Exchange - both parties receive bonuses when researching the a tech from the tree the tech exchange covers (e.g. Economy)
Exclusive Trade - for some time (1 year or 2) both parties can only establish trade routes with each other
Guardian - One party will guard a certain sector of the other party against a race that fares war against the defended party
Retreat - Retreat all vessels from a Sector
2. Diplomatic possibilities
Dipl. Vessels - Can be used to transport delegations to other planets. A delegation vessel will land on the other planet and raises the standing - or espionage - or trade -or lower the standing between two other races (would LOVE that)
More as the ideas are coming, but pleeease give us more options. The diplomatic system is the biggest flaw in the game up till now.