Look at a 60” projection-style HDTV by Mitsbishi. Cheaper than LCD/Plasma, just as sharp, and 3D ready if you want to go that way. We have a similar sized room to what is described, and that is more than enough TV. Plus, we don’t have to deal with having a dark room like you need with a projection system.
The only problem with most rear projection sets besides the bulbs is they are deeper than a flat screen.
They tend to be 15-20 inches deep. A secoond issue is the bulb life. They are $100+ and unless you can replace it yourself (supposedly not difficult) you’ll have to add the cost of a service charge and what ever they add to the cost of the bulb. Still better than the old projection sets that had 3 lamps.