I agree that the bigger the better when it comes to HT televisions.
I sit about 14 feet from my screen, (a 58" Panasonic plasma), and while it looks great, it is difficult to really get a sense of what the 1080P image is really like from that distance, as the DPI is so small.
(However, when I lay on the floor to watch TV, (a habit from my youth!), I am about 8 feet away from the screen, so I can see that the 1080P really does look significantly better than the regular 480P does.
I recommend that you get a screen whose diagonal measurement is half of the distance from your sitting position. (i.e. in your case, sitting 14 feet away, means a 84 inch, (7 feet), diagonal screen.)
My two cents worth anyway.
Good Luck in your search.
PS A plasma, or a projector, is what I would recommend for the type of TV, for the best picture quality, (although a projector needs a really dark room).