Wallpaper or tin in the dining room tray ceiling

No one can give you truly helpful advice UNLESS they see more than a single wall. They will need pictures, and maybe measurements, of the entire room.

I have no idea what the dining room looks like. Wallpaper the tray ceiling--probably not. That's a very 1990's/early 2000's look.

As for some kind of feature wall behind the TV; it already exists with the windows and doors. Painting it a different color than the rest of the room won't add anything. I do see curtain rods above the doors and probably Roman shades. What happened to the draperies? That's a place to add color and texture.

I'd also suggest removing the candlesticks from the fireplace mantel. They disappear and do nothing.

rrah makes great points, those windows are already a lot. I wondered what you have on the windows now since I see a curtain rod and romans. The accessories you do have, including the candlesticks, baskets, sconces and art all seem small for the space. Rocking chair too..

Is there *anywhere* else you can place the TV? It's a grand, beautiful wall, with those windows & high ceiling & fireplace. The television ruins it.

A soft modern print wallpaper could add a little more interest (energy) than a solid paint color. This is Priano wallpaper in Sky from Serena & Lily. In your tray ceiling maybe repeat the same shiplap that you have in this vaulted living room, so you are bringing in a texture and not a pattern.

More pictures would definitely help. We cant see any of the areas you are mentioning. Also, agree, the tv, should be moved. It takes away from the look of that beautiful wall of windows.