We boarded the Liberty of the Seas on a couples trip. This was our 3rd cruise, first on Royal.
We stayed in 1888 on the 12th floor, spa end. We assumed it would be quiet, however there was a sun deck above us that some families chose to convene late in the evening a few nights. Overall, however, it was quiet. We easily walk out to the jogging track and sundeck.
The beds in our cabin were very, very hard. Apparently the mattresses have been recently replaced, and RC no longer offers mattress toppers because they have "upgraded" mattresses.