AV Receiver and in wall built in speakers

That sounds like a decent setup although I don't think that receiver has ATMOS output. If you are going for a nice theatre setup, you should consider ATMOS.
My main setup is an Onkyo 7.2 running in 5.2 ATMOS - front in wall speakers and center channel, rear left and right all about 4 ft high in wall. Active subwoofer on the floor. Then the ATMOS height speakers - left and right in the ceiling over the viewing area. It sounds amazing. I let the system auto calibrate with the mic and tweak it from there. Not a ton of movies that have ATMOS output but the receiver does a good job of rendering standard surround in ATMOS.