We stayed in 6618 - right by the elevator lobby - and it was very quiet. I was surprised. It was also very convienient. We grabbed the stairs everywhere and everything was such a short walk away. We've booked our next cruise in rooms right by the elevators again.
(One thing I didn't anticipate was the stairs. I figured grabbing the stairs on the ship would be like grabbing stairs in a hotel - back hallways, little stairs. But the staircases are large and grand - and get far more use than the elevators).