do you plan to tie the TV into the fireplace or were you just planning to slap the TV on the wall.

at a mininmum, I would construct a cabinet anove the firebox above the fireplace to store the cable box, dvd, etc?

as for finishing the fireplace, it would help to know a little more about home's style.

given the angles coming off the firebox, I hope that your house is contemporary.

why did you contractor create these angles?

I suggest painting the fireplace walls a different color than the exterior wall and using a simple tile or metal surround to trim the firebox. I agree the TV should have a framed cabinet as well to allow for receiver,dvd,etc. Just easier to hide all the wires.

It would be great if you could get your builder to remove those angled sides at the fireplace.....they are not adding anything valuable to the design, but removing them will add space for built-in at both sides. it would also be great to house your tv in a cabinet at the side - rather than above - the fireplace. (I know we see it all the time, but installing TVs above the fireplace is not ergonomically a very good idea.) In the photo below, the doors on the left "bi-fold" out of the way and the tv is installed on a mounting arm at the rear of the cabinet.