I love RCT. I just started playing 2 again and it's still really fun. The only Tycoon games that aren't crap IMO (I think the others all ripped it off that, anyway. School Tycoon? ROFL)
If you do cheats and play in sandbox mode you can make some awesome coasters. Like the one that took 20 minutes to get to the top of a lift hill and went past the background for a while. Yeah, that one went a little bit fast. Then sometimes you can make a launched coaster like that and shoot it straight up with people in it. BOOM! Then your park rating drops like a rock. Most funnest game ever.