Sorry to read about your bad luck with the Newmar coach you had Rodz. My friend had lots of problems with his DutchStar. He was so embarrassed with his coach he did not even want anybody to visit inside his coach. I really felt bad for him being that these coaches cost so much money. That is why I laugh when I read these posts by the same fellows telling everybody that their coach is the best and so on etc etc. I know you can get a bad coach from any company. They are mechanical and they do break. Newmar does make some beautiful coaches, but some are a piece of trash.
As far as quality of materials and some do not understand this. There are different levels of coach lines. You have entry level which will cost considerably less, so you are not going to have the amenities of the flag ship coach line which would have the luxury items. So naturally it will cost you much more.
Chassis not much difference on diesel pushers. They will out last your life span if you take care of them.