wow you have a nice long room, I would recommend to get the largest possible screen that the unit can display well as you have the length to enable large displays. With a really large display you might get one of the newer screens that enable speakers to be placed behind the screen for your center and mains. I have a Sanyo projector shooting to a 7' wide screen and enjoy it but if I had your room I'd go as wide as feasible based on any mounting limitations. Size matters