I never like shelving above a place where you sit. A nice large piece of art hung 6" above the back of the sofea would make more sense BTW thya vent looks like it needs a good cleaning.

Can you post a wider picture of the entire room?

Generally, if you fully decorate the "people" area with curtains, lamps, art, rugs, texture, etc the high ceilings will look light and airy, not bare.

Vents are always somewhat unattractive, but everyone has them. If it isn't already painted the wall color do that as that helps. You don't need to decorate over the 8' height. Keep everything to a human scale. While I agree with Patricia about shelves, if you keep them shallow to display only artwork they can work. Here are some of the ways others have decorated over a sofa:

Wordly in Los Altos · More Info

Classic Living · More Info

A colourful London home · More Info

Pelham Renovation · More Info

Clarendon Residence · More Info

Decorate up to the horizontal line made by the bottom of the vent. You can either do 2 large pieces or a gallery wall. No need to decorate the upper triangular section of the wall.

You can also get decorative vent covers and paint same color as the wall.

I wouldn't do shelves in that location.

Thanks all. I had a large piece up and didn’t like it. Considering either artwork ledges so i can display various pieces or gallery wall. I do have the decorative vent covers but haven’t tried painting them the wall color. Smile.