If your intent is to allow full upgradability to possibly biamp, some day, then go ahead and run 4 wire. It isn't a lot more, and you really only get this one shot with the walls open to run all the wiring inside the walls.
Going much further, you will have to consider ALL your wiring runs now, as well as all your conduit feeds, as well as dedicated electrical outlets on their own circuit for your gear, projection location (?) proper equipment location (not at the front of the room!) Ethernet drops, etc.
I have 20 pieces of coax run to my family room from my basement, and I've found it isn't enough.