The client initially discussed having the hearth on one wall and the television/home theater on another. This is easier from an A/V installation standpoint -- no fire to deal with! -- but inferior from a living standpoint, which we’re told matters. How do you arrange the seating in a room with two focal points, the TV and fireplace?   
You can’t. It’s not how people want to live and we designed the solution. TVs over fireplaces present two problems:  heat and height. Heat is obvious, a melted screen is probably not ideal. We worked closely with the hearth company to manage heat flow -- note how the TV is on a plane recessed from the fireplace. This creates an air gap that among other methods employed dissipates heat.

Viewing height has to be comfortable. The distance of the monitor over the fireplace has to be enough for heat dissipation, but not so much as to leave the viewers with a sore neck every time they watch a film. We simulated the room setup for the client, monitor height, size, and viewing distance to find a comfortable arrangement.
A wrench in the works was the center channel speaker -- it typically sits below the screen in a home theater setup. This would raise its height even further. Our solution -- dual center speakers that flank the monitor and put voices directly where they should be, centered in front of the screen. This allowed the monitor to be ten inches lower -- an ideal blend of comfort and performance.
Equipment:  Paradigm Studio 100 left/right speakers, Paradigm Studio 20 center speakers (2), Paradigm Studio ADP 590 surround speakers, Paradigm Sub 15 subwoofers (2), Anthem MRX700 A/V receiver, Samsung 64D8000 plasma monitor.