If your budget limits you to a 50", and your interested in a wall mount, you might look at the Monoprice articulating mount (with solid aluminum arms). That mount, when fully extended, will allow your TV to be about 20" or so from the wall. If you want it closer, just pull it out some.
IMO, a 50" could work from 10ft. away just fine. I sit about 8ft. at my primary location with a 50" and I've never once thought "I need to be sitting closer, I can't tell if this is HD?" I also have seating 5-6' away and for some people that's too close. You want the image to have an impact and see all detail, etc., but you also don't want to be looking all over the screen to actually 'take in' the image.
P.S. if you're married, your wife would probably not be too keen on having an IMAX theater in your living room.