If you want to take you coach in for service, I recommend Freightliner of Phoenix (technically it is Tolleson). They have a dedicated RV department. Kirk is the manager. Not very social, but is a straight shooter. They have something like six full hookup sites if you need to stay overnight.
The company has a Division in Tucson, but Iíve never used them for service, so I canít recommend them.
We have a Freightliner facility near to us (in San Diego). Tried them twice. Never again! We just plan on an annual service stop in Phoenix when heading out.