I have to be honest with you...we have been on 3 cruises
2 non-connecting rooms- great- both on deck 5- no noise from anywhere.
THEN we got 5522. We had more noise than quiet. We could hear their child crying when they came in late- usually after 12 midnight. She would cry for 30 minutes or more. We could hear what they ordered for room service, could hear their beeper go off, talking, bath water running and splashing- you get the picture!
But we also had a lot of noise from door across the hall where the staff goes in and out of. It is a heavy metal door and we heard it open and close quite often.
I would only stay in a connecting room IF I was with the people who were in the other connecting room. I am sure that our neighbors heard us also- because we are early to bed- early to rise kind or people. I hope that we did not wake them up- we made a conscious effort to be quite so as not to disturb them in the mornings.