Alright, I should be pretty good at parks, let me break it down a bit
Attraction placement- I believe there can be more to this, some parks do this to save some pace for, possibly a future development, and they might need the area. Usually lots of rides = lots of people, making a crowded section. When planning out for attractions, make sure there is space for other rides available, and future planes for the next big ride to come to the park. Also, think about maintenance, is it easy to get too. quick to maintain, can cars even get through there without hitting anything important, like the track it's self, or a important support collum.
Quality/Rides- Simple, and sweet, like this.
Theme- usually rides in a certain area maintain a certain theme, lets take the Oktoberfest area at Kings Island, the rides are quick, and fun, while also being around a more olden style, tombs or viking ship around a lake.
Accessibility- I covered this with attraction placement.
Use of Space- Usually parks try their best to place rides relatively close to already existing path from a while ago, instead of adding new areas. sometimes old rides have to go, why not make use of that.