Which Coaster to Build?

I think I am ready to begin modeling and actual roller coaster now that I have the technique down. The question is which one? What are your suggestions? I am open to wood or steel, just nothing too complicated for the first one. I am try to think of a nice an easy out-an-back coaster. It would also help if I could find blue prints or something with the actual dimensions so I won't have to guess. Help anyone?