Using the x-series (encore for the x-ls and x-sls) speakers would make for a better (all but perfect) tonal match to your mains if you did the x-statik and x-voce at the front because they all share the same drivers (the a/v-series use a different tweeter and the a/v-1rs use a different but similar woofer). Most folks would say for surrounds you'd be fine either way, but it is something to consider if you're chasing max performance first.
You can flip the ports on the x-omni and x-sls (per Danny, IIRC) to the front, so you could put either against the wall if needed. Although clearly not ideal particularly for the x-omni to be up against the wall, in this use case, they're kind of behaving like floorstanding a/v-1rs with their indirect/upfiring woofer (although admittedly the a/v-1rs are designed intentionally to be up/angled firing).
If you went a/v1-rs, I'm not sure how low you'd want to mount them on the wall so that you aren't firing them into the soffit instead of at the ceiling proper (or how that would affect their performance).
At 13' of width, with a 7' wide couch, and if you gave a foot each for depth for the side speakers, you'd have 2' worth of walking space beside the couch to either side. From personal experience, that's enough to walk around it, but for some people (I've got some really big friends) it feels a little tight to move around where 3' to either side of the couch might be better.
If it were me, and the plan was to go x-statik up front, and I had the opportunity where you're at with fresh construction to make running additional wiring easy, I'd actually do 6 of the x-ls encore and run them up near the soffit, wall mounted and angled down to the listening area. You'd have the best tonal match all around and still get the speakers off the floor so no problem walking around the furniture. If you went floor standers, the x-omni would be smaller in depth so you'd have more room to walk, and although they work great as omni mains, I think their original intent when sold by av123 as complete speakers was to be surrounds for the x-statik/x-voce anyway.
Nice room! Congrats!