StingingVelvet: I don't usually use my full res for these kinds of games, even with a mod. It tends to zoom out too much.
For 16:10 I tend to use 1280x800.
I think it depends on the native res of the game...the ones you're used to were probably designed for 640x480 so don't scale well beyond 1280x800. Planescape looks pretty sweet in 1680x1050 for me. I guess it is down to preference too, though.
PhoenixWright: Paul, you're amazing. Everyone, what size fonts do you usually end up with? I think I'm going to try 80% first.
20% is perfect on 1680x1050 for me.