My advice is bigger, bigger, bigger, once you get a big one you want it a little bigger. Get the biggest you can afford and don’t let 720p scare you away, it takes a magnifying glass to tell the difference from 720p to 1080i and 1080p.
Why? If you live in an apt, why spend the extra money? A 32-inch or 37-inch works wonders and it's more convenient.
What size would you recommend for viewing from 10-15 feet away, as in a bedroom?