I'm very picky when it comes to RCT.
I, too like my paths to be on flat land, not on those ugly stilts. I also only like them to travel in a straight line, no wiggly-waggly paths that go every which direction (except for maybe queue-lines). I also like to have lots of hills, trees and flowers to give the park a "closed-in" feel to it. I like to make pretty entrances with themeing, fountains and whatever else makes it look good. I don't like cramped parks, I like to spread everything out evenly. I have a liking for lakes and ponds, too.
I'm also very picky when it comes to roller coasters. I hate using straight track, the most I will ever use is one piece of straight track, maybe two. I also don't like using minimal steepness except for lift hills. I don't live curved drops either because they look ugly. So, in turn, my coasters have a nice, clean-cut look to them. If a coaster doesn't look good, I'll simply delete it and start over, no matter how good of ratings it received.