There are so many "tycoon" games out there (and most of them bad), it's always great to find a diamond-in-the-rough--a worthy successor to SimCity.
Enter Roller Coaster Tycoon. I put the original in, but the later versions definitely improve on the game.
This game is a lot of fun, although it takes some time to learn the physics in designing roller coasters, which can be quite complicated. There are a ton of different rides to use, and if you are ingenious enough, you can create some of the more popular amusement parks. (I once saw a downloadable save game that roughly reproduced Disneyland)
All and all, if you like tycoon and strategy games, you can go wrong with this series.