what would you say your style is ? and color scheme.

Your fireplace is just floating. I'd say add a trim like which is very warm and inviting and adds an expensive look, but isnt really expensive, the shelf on the top would add a barrier between your tv and the heat. but if you still didnt want the tv above the firplace id add a decorative mirror like one of these http://www.houzz.com/photos/products/decorative-round-mirror also adding a area rug infront of your fireplace, and a chair on the side with a nice pillow and throw on it, with and end table and lamp that match your decor will add a nice place to enjoy the fireplace.

but obviously you dont have alot of space between your firplace and the cieling so there wouldnt be enough room for the tv and trim, id say definately add the trim , rug, chair, end table, lamp, and throws.

Thank you Shelby for your suggestions. Should the TV be wall mounted or on a media unit?
How about the space beneath the air-conditioner unit? What do I do there?!

if your not wanting to put it above the fireplace, which i wouldnt, theres only a little bit of space, id put it on a media unit to add do the decor, sometimes wall mounting a tv can be boring and leave you with "the big blank wall"
and hmm let me go look at some idea's for the air conditioner units.

Hi,
You have so much space to the left of the fireplace, could you put your TV there? If you add some invisibly mounted shelves to make a balanced composition... (I've mocked up something, couldn't adjust the 'shelves' to make them look level, but you'll get the idea ;-))

Under the airco unit you could put a tall dresser. I've added one from Westelm that is actually a TV cabinet. Which would also be an option. And if you really want (or need) your TV to be to the right of the fireplace, perhaps you'll have space to place it in the corner.

(I meant to say: in a cabinet in the corner)

http://www.westelm.com/products/shoji-armoire-g837/?pkey=cdressers-nightstands&cm_src=dressers-nightstands||NoFacet-_-NoFacet-_--_-

you cold do a hallway table , which as a longer skinny table in a dark wood that would match your floors and put a lamp some picture frames and a small plant or decor of your choice on it which would distract from the ac unit , also for a more luxurious feel you could add a bedroom bench like one of these i really like the white ones https://www.houzz.com/products/bedroom-benches-prbr0-br~t_546 , and add a few small pillows or throws on it, with a decorative picture above it.

could*

I also like carolins idea:) its very modern.