Who makes the decisions in terms of a new coaster?

I tried searching for forum for a topic like this so if someone can find one similar please direct me, but I have been wondering who actually makes the decisions for new additions such as coasters and rides? For example, when a ride is being planned, who gets to decide on the track layout, or who creates it? I understand the rides are planned years in advance, but if anyone has any information that would be great, thanks!

1. Cedar Fair's Planning Commitee (Matt Ouimet, Rob Decker, Lee Ann Alexakos, and a couple others but I'm not sure exactly who) works with a GM (for Cedar Point, that is John Hildebrant) to decide the type of the attraction.

2. After Cedar Fair has made their initial decision, they send the concept to specific manufacturers (Intamin, B&M, etc.)

3. The manufacturers either design the coaster in-house, or contract out to a third party (for example Millennium Force was designed by Werner Stengal)

4. Cedar Fair decides on the offical location and layout, and the manufactuers begins to build the parts of the ride.

I may be wrong but thats what I have heard.

According to Ouimet, Cedar Fair traditionally gives roller coaster manufactures the dimensions of land they want to build on. After that it is the manufactures job to design what will be build on that land. He continued by saying that in the future he plans to work more closely with the roller coaster designers.

Ok, thanks guys, I figured it was something along those lines but I wanted some more info.