A 65 inch UHD TV on the wall in the den with a couple of Atmos speaker mounted in the ceiling and the Denon X5200W to power the system. The rest of the speakers would be mounted at seat height andd the "biggest baddist and lowest" subwoofer for sub sonic feelings.
I would put a Samsung UE65JS9500 on the wall of my media / computer room. The ceiling in there is accessible from the attic space, so speakers in there would be perfect. Having the Onkyo TX-NR1030 Atmos Receiver would just be the right receiver.
I need it to replace the 20 watts with two 4" speakers built-in the TV. I would get a new set of speakers and a pair of woofers.
Oh a new HDTV would make my den a media room.