Xcode 7.0.1 Simulator Won't Launch?
I had the same problem on my 13in non-Retina MacBook Pro. I fixed it by going to my project, building and running the project, and when the Simulator.app opened, I pressed the "Stop" button. 

This worked for me, but it must be a bug in Xcode 7.0.1 because just a few days ago my simulator was running fine.