1997 (Monaco) Beaver Brandywine 40M

I don't have any direct experience with Monacos or Beavers, but have the same understanding of the quality during that time period as you do.  I do however, have experience with owning an older, yet high quality coach.  The few pieces of advice I would offer are:

• Parts and information: Obviously, with it encroaching on 30 years old, some parts, mostly electronics, will be hard(er) to find.  Records, schematics, etc., may be hard to come across as well, complicating troubleshooting, etc., when something goes wrong
• Repairs:  Getting to this age, certain parts will just start to wear out, and they can be the expensive ones, either in cost or labor (air bags, hydraulic hoses, etc.)
• Labor: Given the above points, someone will need to work on it.  If it is well taken care of and you keep after things as they break, it won't get too bad too often, but just prepare yourself.  It will either be your time or your money.

All of that aside, I think owning an older, high-quality coach is a great thing.  A well cared for one, to boot, sure makes it cool.