I have a Sony 40" 1080p tv that I use all the time for my PS3 in my bedroom, and it's not worth it past about 6 feet. I can tell the difference between 720p and 1080p within 6-8 feet, but further you can't tell really. Most games are 720p anyway. Unless you really want 1080p for Blu-ray or to be future proof, I'd save the money. I regret splurging on my tv. Or if you make really good money and find a great deal on a 1080p get one. Otherwise go 720p.
p.s. Get a hdtv with a high contrast ratio though, that's important.