mtofell1 -
1. Make sure you get a well built model and not one with known design problems. Keep in mind Beaver, Monaco, and Newmar have big lines with lots and lots of models. The quality of design and component quality with differ significantly between models and size within those model range. Meaning some coach lengths will have good chassis length and enough CCCs and some will not. There is a huge difference between the bottom end of the Beaver or Monaco or Newmar line and the top.
2. Buy a coach that the owner has taken care of. If everything is working well and in good condition when you buy it you only have to fix the new things that go wrong.
3. I would suggest adding Country Coach to your list.