Sounds exactly like my room. Check the pics in my signature. Everyone I talked to recommended putting the screen and mains on the short wall. While it sounds very good that way, the location of the screen is entirely too low. The location of the door and media closet in my room makes turning the room around impossible, but if I didn't have those limitations, I'd probably turn the room around. (Note though that if you do it this way, there's no way to get two rows of seats in the room as you can't elevate the back row when the ceiling slopes down to 4' in the back of the room. (in my room it goes up to 5.5', but it's still too low)
Jason