Help buying a television

My girlfriend and I will be moving to a new house, and the room for the TV is much larger than in our current setup. She loves football (yes, some guys do get lucky), so the NFL via DirecTV will be the primary focus. We'll be about 12 feet from the screen. From what I've been reading a 50- or 55-inch screen would be about right for that distance. Also, I've read that plasma is still thought of as best for sports.
Do these bits of information seem correct? Anything else we should consider? Recommendations -- including brands -- would be greatly appreciated.
FYI: I posted this under "Home Theater" because that made the most sense. That said, this will be a set on the wall, not a real home theater.
Thanks so much for your help.

-- Howard