Moved to a new house a few years ago and we have been slowly renovating it. Priority was getting the HT room setup. All of our HT equipment came with us from our last house. Previous owner was using the room as a TV room, but it was poorly done. Room is 18' x 21'. Owner had a 5.1 setup with the TV mounted in the corner of the room, speaker wire just poking thru holes in the wall that someone had made with a hammer. Room had no light control with an open passage into the kitchen and several large windows. Here is what we did.
1. Framed open passage for a set of 8' tall mahogany french doors.
2. Replaced closet door to match the french doors.
3. Painted walls and ceiling with matte paint.
4. Disassembled, stripped, and painted 4 air vents and one intake matte black (This was a major PITA)
5. Installed new taller baseboards.
6. Installed wiring for 7.1 running into the closet.
7. Installed Cat6 drops in each room of the house possible and ran those to the closet.
8. Installed equipment rack in closet.
9. Installed 3 layers of window treatments for total blackout.
10. Installed Haiku fan from Big Ass Fans.
11. Installed custom theater sconces
12. Installed Philips Hue light bulbs in the sconces and recessed lighting.
13. Installed front loading movie poster frames.
Ideal wall speaker placement for 3 of the 4 back speakers was problematic due to the location of the windows. I opted to hang the speakers from the ceiling rather than place them on tall stands due to dogs and young children in the house. While the pictures don't show it clearly, the seating is in front of the rear speakers.
Currently shopping for a new projector, probably a Epson 5040 or Optoma UHD65. Then I'll evaluate whether or not a new screen is needed. Currently use the PS4 Pro for blu-rays, but since it won't do 4k blu-rays I see a player in the near future. In the mean time will watch some of the Netflix and Amazon 4k content thru the PS4. Open to suggestions on improvements.