Age of Empires 3, Company of Heroes, C&C3: Tiberium Wars
I think they're good. AOE3 has the RPG levelling up your home city for more cards aspect, which is fun and should keep you busy for a while.
Company of Heroes has really good gameplay. Flanking, fast tactics, all that. Don't let the WWII setting put you off.
C&C3 looks great and plays well. The campaign is good fun and it's always fun to roll out Mammoth Tanks non-stop.