Sorry for the late reply

You guys are on a roll. It's been 3 or 4 episodes now of straight (and positive) strategy talk. Keep it going!
Map trading is bad. Madd hits it on the head. It takes away from the exploration aspect. Shared maps should probably be resigned to alliances and even then only owned territory. This very thing ruined the exploration in the new MOO, because everyone you meet wants to trade maps and when you don't, your standing goes down. Very bad idea.
I think the research agreements work fine as implemented in 6. A boost or set amount of research along with a steep gold cost is fine.
Wonders in BE were initially pretty bland, but after the pass they made, there were significant improvements. Dare I say most were creative and desirable. The only issue was where they were on the web... The ones on the fringes needed to be more powerful because of the effort involved.
In 6, they aren't bad. They work. The issue with 6 is being able to secure them.
Gold gained from deleting units should be equal to the value pro-rated for health. Value being based on tier minus a percentage (maybe 15-20% like a sell value) such that it will never be profitable, but compensary in nature. And this should only happen when a unit is in your territory as mentioned.
An option for excluding certain civs and city states when creating a game is long overdue. For example in Civ V, maybe you want to things to be random, but exclude Venice to keep city states from being bought up. Or maybe you've seen a certain civ consistently and want to look at someone else for a while.