Large piece of art. Paint the vent the same color as wall so it is not so visible

The high ceiling speaks for itself art should be hung at eye level no matter how high the ceiling and I agree art above the sofa and paint the vents to match the wall and if you are careful to get art that is more horzontal you will not cover the ventBTW books on a shelf over a sofa makes no sense in fact shelves over a sofa don’t either. Since the room is sort of monochromatic maybe a black and white piece with one pop of color in it that you could use for a throw or pillows

Agree with Patricia. For more WOW, drapes flanking the window like below.

I would have an HVAC company move the vent over and get a over scale mirror. Check www.RestorationHardware.com

Those are really crappy places for vents. With all that wall space, forget hanging art on the wall. Hire a muralist! Make the wall the art.

Joe

If you can't afford to hire an artist, do it yourself. These are ideas for inspiration, not necessarily direct suggestions:

https://www.houzz.com/photos/wall-paint-ideas-phbr0lbl-bl~l_36996

Some of my favorites:

Bold

Urban Cabin Fabio Galeazzo · More Info

Less bold

Jen Going Interiors, Holiday House Hamptons 2014 · More Info

Subtle-ish

Colour in our Residential Architecture · More Info

Joe

At very least, paint the vent grates the same color as the wall.....

Your wall requires a treatment that will allow the placement to be placed around the vent. You need a collection of some type of objects that can be scattered vertically on the wall. Here are some examples.

Is that a mirrored coffee table? You could do another mirror above the couch. Definitely need something to fill that space and balance out that tall wall. A mirror would help reflect light coming in from that window.

Consider a tall, vertical wall hanging, some sort of fabric or such, centered between the vents and under the high point of the ceiling. And assuming it's too expensive to move the vents, at least paint them to match the wall.

You already have three mirrored tables. What would a mirror on the wall double? Is it something pretty or interesting? If not, then add art for more interest.

When I was looking for the right picture for my wall, I went to furniture stores and Pier 1 on a Friday asking if I could return them on Monday if they weren't keepers. They all said yes. I was so helpful to actually see it in the room.

The right picture will be a wow. You must not have found one that is perfect for the spot. Keep looking.

It could be hard because you have no color other than gray. Try introducing a color that will give your room that WOW factor.

We carry many large artwork that can emphasize the height (see sample below), but you can't do it with that vent in the middle of the wall. Any way you can take it out or move it? I wouldn't hang anything over it, even if the grid is tight because heat still gets out.

Check out our site for ideas of large artwork but I wouldn't do anything without fixing that vent.

www.ShoaGallery.com