It looks like an area that is a main corridor so I wouldn't use ledges. Instead, I'd get a large, square (48"x48") colorful piece of art, and paint the vent the color of the walls. You can also use 3M removable picture hangers, which will allow you to change pictures out frequently with no damage to the walls.

An easy and modern look is the idea below. Ikea frames are inexpensive and purchase Bristol board at a craft store. Cut off centered to fit your photos of vacations, family, scenery, etc and they can be easily updated. The wall won’t feel cluttered or too busy either.

Thanks Sammie J. I had thought about the ledges sticking out and being in the way. It is a high traffic area leading from the kitchen back to the bedrooms/bath.

I would do one oversized piece of art on that wall I really usually dislike gallery walls and never like them filled with family pics so after they are done usually just look like a mixed bag of stuff .