Bigjoe5, I think that a simplistic model like that is far to limited, you've cleanly divided trade and alliances into two separate things, why? Why shouldn't I trade a "full defensive alliance" for 100 gold and 50 production points in the same treaty....
I'm not sure bigjoe is making that point. There's a distinction between "having just a few general options" (which i more or less support) and being able to bundle those options together in a single treaty.
In theory, i like the idea of being able to bundle things together in a single treaty ("yes, i'll sign the peace treaty if you declare war on my enemy.") However, in practice it can be troubling.
FreeCiv (last time i played) has diplomacy like this. They have a reasonable number of diplomatic options, but when you combine them all together, there's a virtually infinite number of combinations. I know that will instantly appeal to some of you, but think....
In MoO2 if you want a particular treaty with someone, you can find out in seconds if they are will or not. On the down side, there's not much you can do about it. On the plus side, you can't waste much time reshaping a treaty that will ultimately be rejected.
With FreeCiv you can spend a very long time refining the treaty, trying to avoid giving too much away, but still trying to get that shared vision, or maps, or whatever. You can never get an absolute "No," but can spend a long time trying to get close.
It might be possible to make a diplomatic interface that has proposals and counter-proposals to quickly refine a treaty down to something that could be acceptable to both parties, but i haven't every seen such an interface, i don't know how exactly that could be done.