I remember I played a ripoff game where you design a whole theme park and have to make sure your customers like it. Very reminiscent of the Sims, elements like if you didn't have enough bathroom your customers would leave, etc... Designing coasters was just a side part of it.
For RCT do you design other parts of the theme park to keep the people happy or just coasters period?
IGN link:
http://pc.ign.com/articles/544/544581p1.html