Thanks for the comments, some good ideas to consider.
I'm now thinking that to start, there will be a couple 4K TVs and a legacy 1080p TV. A 4K set in the living room would have its own receiver for a Dolby Atmos system, while basement 1080p TV has its own receiver for 5.1 system. I can house these receivers in a closet.
To keep it simple for the time being, I may just focus on getting the HDMI signal fed from other rooms to the A/V closet to their dedicated receivers. Does it make sense to run conduit for HDMI fiber, or will Cat6a suffice? I want to future proof for HDMI 2.1 but these cables aren't really available yet, so might settle on 4K HDMI extenders that can handle 4:4:4 at 18Gbps to handle [email protected]
with HDR, then just use 18 Gbps cables for TV/receiver to the extenders. I can implement a video matrix later on if it makes sense from a price perspective. Also, some of these new receivers have extra HDMI outputs so I could use this instead of buying a matrix.
More important I think is the multi-zone audio, so may go with a 6 zone controller/amp with keypads/volume knobs. The most important zones are the patio and dining room, and for sources I may use airport express's to take advantage of AirPlay 2 capabilities. Are there any major downsides to this path vs. going the Sonos Amp route?
For video control, I plan to use IR extension via the HDMI extenders to get remote control signals down into the AV cabinet to change volume / sources / control cable box. Could use a Logitech Harmony style system to control media.
For audio control, if using AirPlay2 should be able to pick and choose the rooms through the native AirPlay interface.
I'll have to diagram this all out at some stage but want to make sure I make the right decisions early re: in-wall wiring before it's too late.