Since you have a very high ceiling, it might be good to take the eye across the width of the room with extending shelves clear across on each side of the fireplace. Do make sure that if mounting the TV above the FP that you will be able to watch it comfortably.

How far does the room extend back from this wall? It would be better to build in a TV shelf to the right of the fireplace instead of trying to place it above. You could have doors that pull out from each side of the TV To cover it when not viewing it.

Also paint the heat/AC vents on the left wall to match the wall color to make them 'disappear'. I would like to see another row of pictures below the row you have above the sofa.

Thank you for your suggestions! The room is quite deep - 20 feet. Currently our couch is 12 feet from the wall. Is there a recommended distance/height for a t.v. above a fireplace to be comfortable for viewing? That has been a concern of ours.

Food for thought: Your room is very narrow-have you tried putting you existing furniture the other direction to see if you have enough room?
Please research about putting TV above a fireplace. TV don't like heat and there are other considerations as to where components will go, wiring, etc. Another thought is to not mount it too high. Otherwise you will have to lean your head back. Find charts on Internet as to proper height and distance based on TV size. I

http://www.portablefireplace.com/blog/tv-above-fireplace/

Facts you may not be aware of in regard to TV over FP.

Unfortunately, there is an office door to the left of the black couch (I attached a new photo to show.) So putting furniture there would block entrance to the office. Facing the tall wall seems to be the only option (our plan is to get a sectional to optimize seating...)
Thanks for your suggestion though!