great article, just incase folks dont read it here is a clip from it "Will the heat from the fireplace harm the plasma TV? There are a few precautions to take before hanging a plasma screen TV over your fireplace. First, take a thermometer and tape it to the wall above the mantel, in the place where the plasma TV will reside. Then build a fire, and let it roar awhile. Now, check the thermometer. If the temperature is above 90 degrees F, then the area is receiving too much heat -- either escaping from the front of the fireplace and rising up the face, or radiating through the chimney to warm the outside wall -- for a plasma TV to hang there without receiving some modicum of residual damage. It would not be advisable to run the plasma for a long period of time while its environment is this hot. Though the Plasma TV has its own cooling system, the surrounding heat will force the Plasma display to work harder to cool itself, thus shortening the overall lifespan of the unit over time. A Plasma TV may still be run for short periods of time without harming the unit (even with the environment heat at 90 degrees F or above). If the plasma display is not turned on while a fire burn in the fireplace, then the unit will not be harmed at all even though the temperature surrounding the unit may be warm. Of course, this might not be an option for people living in places where winter lasts seemingly forever, and fires are an everyday fact of life. In such cases, you should be advised to monitor the amount of heat your plasma display is exposed to while it is running."

Are you planning a wood burning or gas fireplace? If wood burning this one seems like a great option for linear without being too modern - we looked at it but concluded we needed more height (and we're not dealing with the constraint of a t.v. over the fireplace, as we're generally not a fan of that, aesthetically or functionally). http://www.heatilator.com/Products/Longmire-Wood-Fireplace.aspx That said, I would really consider an arrangement as in your first photo, with the t.v. next to the fireplace.

Not a Pro. I agree with above about the tv. Above the fireplace I would put a painting over the top of that alcove. From the pictures it looks like there is a ledge, so the art can be place over the top and it will appear that it is on a wall. The other alcove I would add shelves, or a sculpture, lighted up as suggested above. Some inspiration:

This often comes up on houzz; I’m wondering if anyone likes their tv at that height in a room that is approximately this size. I have a similar set-up in my soon-to-be new home, so I will be following you. The builder placed the tv outlet above the fireplace (not a low profile, in my case.) It would be much easier to arrange the furniture if I went with what was intended...but I, too, am worried about the angle for comfortable viewing. Not sure I would like to see a tv that is angled downward, and I agree with your concern about using the style that must be pulled forward and downward. I hope we both find a solution! Good luck in your new home. I’m envious of your windows!