An asymmetrical gallery wall would work very well in your space.

Artwork · More Info

Something seems weird with the layout - can you post a floor plan of the entire room, and pics of the other walls?

Can you slide the couch down to center it on the window? Then, switch the positions of the single and double chair. I do not think just decorating the walls will help much. You have some very large pieces of furniture in a not-so-large space. but I think reconfiguring their placement would make a big difference.

I would make sure to pull the couch forward away from the wall so it's floating in the room. Then it's less of an issue whether it is in front of a window or not.

Your space is currently very neutral with mostly gray/white tones and only warmth from the wood floors. I would look at adding some side tables in wood (stained or natural tones, nothing gray or black) and some colorful art. Ideally large pieces. I've been printing up some of my own landscape photography from trips and framing and I'm loving how much color that can add to a space.