I would go for a yellowing color/tone. You have a lot of cool colors already. A yellowish color will warm up the space.

Wall colors are usually based on the fabrics used in the room. Or you can use art or a rug to establish a direction.

From your picture, I would paint the walls exactly the color of your sectional (gray?), take down all of the wall stuff and chose new pillows. Try adding a touch of red.

Accessible Beige by Benjamin Moore would be a good beige as it has a slightly pink undertone that would pick up the color in your pillows. I wouldn't go a light blue, as that seems more in keeping with bedrooms, IMO.

Is your sofa gray or beige? That would probably determine your wall color.