Thrillville has some cool video games blended in with the 3-D park building experience of RCT 3. You get a few other games out of thrillville, but if it's just pure park building you want, then go with RCT 2.

Mind you, I don't think you can share game files, import custom scenery or stuff like that with Thrillville. RCT 2 does give you that advantage though.

Listen to Wolfman, he is smart.

*Im smart too, though *