| Well, if you're looking for simplicity in your RTS, the Command and Conquer games are classics now. The newer ones (Tiberian Sun, Generals, Red Alert 2) are horrible, and I recommend sticking to the older, better ones.
Unfortuneatly, there hasn't been a whole lot of activity in the form of decent RTS of late. Now that Blizzard is working on WoW, we probably won't see another good one from them for another couple years, and EA has basically destroy the original RTS.
If you look hard, you might one or two decent ones out there. I've heard some good things about Savage, which is supposed to be RTS/RPG. | 
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