6556 was our first cruise stateroom and it's FABULOUS! It is only one floor up from the kid's clubs and that above all else makes it super convenient. We had a shock in moving to aft Deck 2 last time and the long hike home w/sleeping kiddos!
There is NO noise in the room, there is no one directly across the hall (the stairwell is there so it's just a wall) and the elevators are close, but no noise comes from that area.
If we were doing Cat 6 again, I would ask for this room in a heartbeat. You'll love it
and yes, pull down berth for the extra sleeping bed