We get these posts continuously. I have come to the conclusion that open space multipurpose rooms are not suitable for surround and Atmos etc. You must have a tolerant wife. These are multipurpose spaces, and you have a massive conflict in terms audio and Interior design. Multichannel AV systems really need a dedicated space in my view. In spaces like your, less is better.
I was not intending to put a system in our great room, but my wife insisted and further said no floor space was to be taken up by the system. So I designed a 3.1 system with all speakers in wall.
Like your space it is a very large multipurpose space.
In your plan those surround speakers on stands, are just begging to be knocked over and sent flying, and they really upset the architecture of the room.
A big pint I would make, is that a good 2.1 or 3.1 system gives you 95% of what is required. In fact in those sort of space I suspect that those multichannel systems like those are substantially inferior to systems with just good front speakers.
The system above fills that large space easily, and with power to spare. For visitors that tends to be the system here that draws the most interest. I think it is because it is way, way superior to sound bars that practically all are using. I am more and more convinced that comlex AV systems do require a dedicated space. So we have a dedicated space for our full blown all out system.
So, if you have a space you can build out, like a basement space for instance, then put the multichannel system there.