Buy LED, LCD or Plasma

If you put it above the fireplace you have 2 problems. Looking up at a screen is not a good idea for extended viewing sessions and it looks like you would be sitting too far away to see the detail on anything but a huge screen.

What are you tying to achieve? Some casual viewing or a home theater experience. I can't tell from the picture how far it is from your seat to the fireplace but just guessing it is about 20 feet. For a total immersion experience it is generally recommended to sit 1.5 to 3 times the screen width away from the screen so you are looking at a minimum of about a 6 foot wide screen. That's about 80 inches diagonal. Above 65 inches flat panel TVs are very expensive so you should consider projectors at that point, but 65 inch TVs aren't that bad with some coming in at less than $3,000. If you want home a theater a better idea would be a projector with a drop down screen between the speakers.

LED tv's have a dramaticly different look to the picture than most tv's. Perhaps its their very high contrast ratio with boasts of 2,000,000 to 1. The clarity is huge, but it looks unnatuaral to my eyes, and over time, became a source of distraction. I notice in tvs ads that they are describing the image as hyper real. Make sure you give it a good demo or check one out at someones house first tro see if you like it.

I'm going to put TV over fireplace as well when current (since 2000) DLP TV dies. I don't care much for plasma. It looks worse (losing contrast) in bright light than LCD, has horrible reflections, is prone to etching a pattern (sidebars) effect and wastes a lot of power. In addition it doesn't die gracefully by loosing contrast but by burst of cells that make dark stains.

Get largest LED LCD. Electroluminescent backlight have tendency to vacuum dirt (high voltage) that eventualy lowers screen brightness by lowering/briging high voltage (case of my IMB laptop). LED backlight should last almost forever.

I don't quite understand distance argument. 60" should be good for 20 feet or more. As for brands - I have good experience with Samsung (two TVs, two monitors) but heard of bad experience with Toshiba (friend, sister-in-law). Sony is overpriced and Panasonic is pretty good (bought one for my daughter).

The only concern I have about fireplace is that TV will be higher than the speakers (TV sound coming from the bottom) but it is very minor complain. Wall above fireplace is, IMHO, the best place for TV.

I don't quite understand distance argument. 60" should be good for 20 feet or more.

You can google "tv viewing distance" to find lots of info but here is one from Crutchfields site

http://www.crutchfield.com/S-IevFNuLGC81/Learn/learningcenter/home/TV_placement.html

Screen Viewing distance range
26"______ 3.25-5.5 feet
32"______ 4.0-6.66 feet
37" ______ 4.63-7.71 feet
40" ______ 5.0-8.33 feet
46" ______ 5.75-9.5 feet
52" ______ 6.5-10.8 feet
58" ______ 7.25-12 feet
65" ______ 8.13-13.5 feet
70" ______ 8.75-14.75 feet

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Plasma if you don't have any bright light shining on it,LCD if you do.The LED's are controversial about color accuracy. I've read some only use LED's for part of the back lighting. There are two types of LED's.The newest LED's may be better, but I'm not sold on them yet.This link helps somewhat on the different LED's.[http://en.wikipedia.org/wiki/LED-backlit_LCD_television]