Wow....my first impression is to say centered with fireplace and then use something on the right to balance out the rest of the blank space. Now, with that said, I think if you painted the entire upper area a really dark color it would help minimize the whole effect. Once you see that black rectangle it's going to be VERY STARK against your light colors. I would probably choose 3 intensities of the same hue and paint the darkest up top top...........then mantle...........and then around tile at bottom. But that's just me :) !! Good luck!

Must be centered on the fire box as that is the first thing that your eyes are drawn to.

thanks! to add some more information . we are inserting the tv into the wall 3 " and the tv is more rectangular shaped. also, we are considering putting stone on either the entire wall or just mantle and around fireplace and hearth (we are removing current marble and the current color is drywall only - no paint on it yet) and painting top wall or???? thanks again!

Measure it out with painters tape first or chalk first and don't guess what would look right. You may decide a bigger tv might be better. Not sure what size you are thinking about.

I don't know if that is a load bearing wall to the left. If you could remove that proportion and make surface flat you will be able to center the tv. Ps. Do not put the tv in the wall. TV/ technology moves so fast that it will not be worth it in 3 years. Buy a low profile bracket and TV. It will be more expensive to change the pocket down the road.

I might add a wood stack next to the right side of the fireplace to stretch out that space and then the pix would not look so weird. It would be the esaiest and cheapest solution.