Thanks for the feedback.
A couple of further questions now as this weekend I discovered Dolby Atmos. I have been reading as much as I can but the 201 page thread is rather intimidating.
1) Is it possible to use the ceiling speakers in the family room for both whole home audio and Dolby Atmos? My original plan was to have two separate audio systems in the family room: the ceiling speakers driven the WHA system (perhaps Sonos) in the server room and a standard 7.1 setup driven by an AVR in the family room. Can I still do that but share the ceiling speakers between the two devices? If so what do I need?
2) Since I will have the whole ceiling open should I pre-wire/vapour barrier box for additional Atmos ceiling speakers at the same time? And are there recommended locations for ceiling speakers beyond the initial 4? The cost is pretty minimal to rough in a few more locations now, I just don't know where they should go.