Our noise level depends on a couple of factors, primarily how smooth or rough the highway is and what direction the wind is blowing.
With the wind at our back on a nice Interstate highway, the quiet of the coach is absolutely amazing
. Punching into a 20 or 30 mph wind, the noise level is very annoying and tiring over the course of a day's drive. This noise is not of the creak/groan variety but just the rush of the wind.
When we are on a road where the coach rolls around, I think we get some frame and house twisting and I do hear the occasional metallic clunk; one noise in particular happens somewhere on the starboard side forward and sounds like it might be related to the slide mechanism but that's just a guess. It is intermittant and inconsistant so we mostly just ignore it.
On rough roads we sometimes hear our new roll-up screen door screen rattle inside its carrier. Sometimes the curtain track carriers rattle, sometimes the pull down left/right shades flop around.
Yesterday on our drive from Tok to Valdez there was the usual construction and even a few frost heaves here and there. One in particular didn't get noticed for its severity and we hit it going too fast (too fast in this case meant we were going 30 instead of 10 mph) and I heard the loudest clunk from the front end I have ever heard, however I think it was a normal sound for that situation.
Our driving instructor (we took Dick Reed's RV Driving School class) was really impressed with the quiet of the cabin and he has literally been in dozens and dozens of coaches.
I think the suggestion of getting somebody to ride with you that is more experienced in class A's is a good one; or try to do a test drive of a similar coach or even another brand. It's difficult to know if your coach noises are usual or unusual.
There was just a topic on rv.net a couple of days ago asking the question of how quiet was your coach. Virtually all of the posters reported that they never hear any noise - my conclusion is that most of them must be hard of hearing. Probably the Prevost or MCI bus-type coaches are significantly quieter than the usual class A, but they also cost mega-bucks and weigh 10 to 20,000 pounds more.