Civilization III would be good if you've played Civlilzation II, but the game differs a bit from II and has better graphics.
The Sims and the expansion packs are fun to play. I think it is kind of neat to have little computer people you have some control over their lives.
Master Of Orion 3 is now out, I heard it was great. If you liked Civilization, you'll like Master of Orion.