I only have a 36" CRT at the moment, but just going by my own experience I'd avoid the rear projection TVs. I've gone to several people's houses to watch big games etc and I don't care for the picture quality. Always seems dim and kinda fuzzy, and they take up a lot of room.
If ya got the bucks, plasma or LCD would be the way to go. Nobody seems to know what the longevity of those sets is, though. They haven't been out long enough. That's the only issue I would have, except for the possibility of burn-in.
Well, that and the fact that they're getting cheaper all the time. Buy one now for $3500 and next year it costs $1500. That's the way it goes with evolving technology, I guess.