I have my set mounted over a fireplace, using a tilt mount that allows the TV to be basically perpendicular to my line of sight. The wire-hiding was made easier by the wall above the fireplace being drywall on studs. So I used a "Power Bridge" set of wall plates/fixtures to bring power over, and also multiple HDMI cables. But I still had to deal with the issue of getting past two studs, to get "around" the fireplace.
One idea that may also be pertinent to your situation is that I used my wooden mantle-top as a routing area for the horizontal portion of my wire runs. I brought power and HDMIs down from the TV to the mantle top, and then from the end of the mantle top I went back into the wall, to drop down to floor level, bypassing two studs. I also ran speaker wires from the right end of the mantle, over to the left end (for the left-front speaker), and also to a hole going down through the mantle for the center speaker wire. (My electronics - incl. receiver, cable box, blu-ray player, plus a turntable, are in a basic A/V rack that sits to the right of the fireplace - just to the right of my right-front speaker.)
The center speaker is mounted on some brackets that in turn are screwed into a facia board that is just under the mantle.
So at that point I had the vertical runs of all wires inside the walls, but a lot of wires running across the top of the mantle. So I made a new, false, mantle top. I put some 1x2 strips on top of the sides and front edge of the mantle,creating a kind of wooden fence around the wires, with a few extra little pieces of 1x2 spaced out on the rear edge of the mantle. Then I laid a new piece of 1x8 (actually only 7 1/4" wide) across the top, and trimmed it out with some decorative molding (slightly wider than the thickness of the 1x8), so that all of the wires are covered up. If I ever need to get at them for some reason, I just need to pry up the new top board. Once painted, the mantle is a little thicker/taller than before, but looks like it was built that way from the beginning.
On the other hand, if my fireplace had been brick all the way up, I don't think I would have proceeded with mounting the TV above it!
But WAF (wife acceptance factor) can be important. My wife is happy that the corner where the TV would otherwise have been, is now freed up for an easy chair. And actually the sound of my Def Tech bipolar towers is improved by having them a bit in front of a flat wall, and not in a corner arrangement. My wife is not crazy about the size of the speakers, but that is her part of the compromise...