I have both Pro ATC/X and Radar Contact and they work very well for IFR flights. They even put controllers in normally uncontrolled airports BUT, unless a person wants to fly by IFR rules on a VFR flight, we are left without controllers it seems at several airports that are controlled since P3D didn't provide them.

 

Right now, I'm trying to investigate how P3D implements ATC and it looks like a very involved task. I had hoped that there was something like .cfg files for each airport but, that does not seem to be the case.

 

I guess I'm hoping that one of the more experienced users can come with a method they have used, sort of like copying aircraft from FSX to P3D, for this. Otherwise it's into the SDK and learning yet another API and perhaps even a new programming language variation...

VATSIM is the first thing that comes to mind.  You can file a VFR flight plan and fly that way if you want the ATC experience.  I have just about gave up on Pro/ATC-X since it is still buggy!  I have found that VATSIM works just as well and is free!