I've always been a big fan of the Roller Coaster Tycoon games on the PC. This takes it to the next level where you can actually play the games offered by the type of building. The Mini games work well, the few I've played so far work well with the Wii Remote and being able to explore the park as a visitor adds an extra dimension to the game.
Building the roller coasters with the remote can be a little clumsy at times, getting the track to go in the direction you want isn't always as straight forward as you'd like it to be.
I'd highly recommend this game, one of the best on the WII so far.