MarkSJohnson is the founding President of the "My Room Sucks" club.
That is an interesting concept - changing the fundamental shape and dimensions of the room via the sheetrock stage instead of with bass traps later. You'd need one of our scientists. Did you check out Randy's "Superchunk" thread? Lots of good treatment counsel there.
Will you be running wire for a IR Receiver/Emitter thing? It seems like you'd want to be able to aim the remote at the screen rather than behind you at the equipment. Just a thought.
Good luck. Take pictures!