Welcome to the forum 8starsofgold!
I think you got a good deal, at least in my neck of the woods it would be.
140,000 miles suggests to me that the previous owners enjoyed using it and you mentioned that it's in good-very good condition so they also enjoyed taking care of it. For chassis maintenance, I'd look in Chevy owners manual to see what should have been done by now.
I recently bought a motorhome that I didn't get any history with. I'm going to book it into a Ford dealer to change the transmission fluid and flush \ replace cooling fluid. Both are due on mine according to the manual. I'll get an oil change at the same time.
Roadtrek Owners Manuals are available for download in case you don't have one:
There's an active group of Roadtrek owners on Yahoo: http://autos.groups.yahoo.com/group/roadtrek/
As for the coach part, keep it cleaned, waxed etc. Silicone spray is good to use on all rubber seals on doors and exterior compartments. You can buy a hose attachment names "tank saver" to flush out sediment an calcium build up from your water heater.
Keep all battery terminals cleaned and well coated with a protective grease. If your batteries take water the keep them topped up with distilled water.
Hopefully some other members will have some suggestions for you.