Well.. there is always a heavily modded FS2002pro but that takes a lot of computer since the mods will choke the biggest race horse anyone can screw together.
A fave of mine is Ghost Recon.. Squad based infantry tactics/ first person shooter, realistic sounds and lovely blood splatter, great for relieving stress after dealing with assholes all day.
I loved the sims but found it to be too addictive, sit down to play it for 5 minutes and 3 days later after not sleeping people start to call wondering if you died. I gave my copy away to someone just to get it away from me.
Sim City 4... AWESOME game.. loved it, just like the other Sim Cities but much improved upon again.
Older stuff: Command and Conquer Red Alert2 is good... another good way to pass a rainy saturday and it takes less time and aggrivates girlfriends less than flying a 777 ORD