Sins of a Solar Empire. Bonus points for using Danman's 7 Deadly Sins mod.
I was playing some Medieval 2 here recently as well... that game's pretty fun if you can look past the horrible pathfinding. Looking forward to Empire total war here next year.
The Dawn of War games are fun for a little while.
World in Conflict is pretty epic actually, you might like that.
I'd avoid anything Supreme commander.
I'm a fable junky, so Fable 2 is a good choice for RPGs... but really I don't play rpgs much.
Sins of a Solar Empire has held my interest in RTS games like no other.