What are some good modern-day simulation games?

I grew up on Sim City, and the Tycoon series. Sim City petered out for me over the years, since the gameplay didn't really change. Sim Life, Earth and Ant were sweet but essentially one-offs. The Tycoons had amazing depth, but over the years they felt more and more shallow. What are some good modern-day simulation games? Any platform from Flash to PC to 360 is fine...