We drove a 2013 Jayco 32 ft C for two years, and wanted to move up. Drove 3 different 36 ft class A units, and found different levels of noise, settling on a Tiffin 36LA. It's really pretty good in this area, also now has the 6 speed tranny which even helps more at highway speed.
Most times, we speak in our regular voices to each other, and also there is a lot less rattling and squeeking of other components.
The best advise anyone can give is, drive the model you like and compare to others in that size and type.
Good luck!