I've been told the eye can't differentiate 720 and 1080 at 32" and under although 1080p is true HD tv.
32" at 7ft should be ideal to take in the full picture.
Just go to the store and look at various screens and resolutions from 7 feet to find your own preference though, probably easiest.
I've been happy with Sony. Great quality, no issues 4 maybe 5 years in. 46" 1080p, 120 Hz
Don't skimp on cables either, you actually do get what you pay for.