Not every wall needs to be decorated. You could easily put a large tall plant in the corner next to the window. Home Depot usually has good ones for not too much. Any of these would work well. Every room needs a plant. They're great space fillers without looking contrived. They really cozy up a room.

How are the acoustics? It looks like a reverberating HELL to me. You need a rug and a lot of soft surfaces to absorb the noise, more substantial drapery for a start. The art in a picture posted above on canvas with a soft look, mostly canvas no glass, would help-a few of them!! The tall wall will disappear if you give eyes something lower to look at.

Roopa if you bought that oriental rug with the bright red and the aqua background, I would go with a pale aqua or pale blue wall. Off white, pale yellow or cream works very well too. It's the daytime light with all the beautiful windows you have to feel airy during the day and a pleasing wall color to look at night and enjoy, not overpowering!

It is a 'real' fireplace..it just has a gas starter which are SOOOO nice for eliminating the messy of getting a wood fire started!! The bottom line is in a room with a fireplace and a TV the seating needs to face both for the room to be used to its fullest. Fireplace/TV side by side is the most aesthetically pleasing positioning. BUT the OP doesn't have that option anymore. When that TV dies I would consider putting a new smaller one to one side or the other. For now a shelf makes the most sense to me. A random light fixture for no purpose seems like a missed opportunity for storage. The added COLOR by Celery, to that space is my personal favorite suggestion. I do not understand half the seating in the room with it's back to the TV/fireplace. This room gives the impression most of the TV watching happens in the kitchen/dining area, Why else the need for such a huge TV with little seating in the actual room?