Lisa, I think the first thing is to clean the surfaces. Check for
safety problems in all the systems. Make sure it doesn't leak water
anywhere - get a ladder and get up on the roof. Check ALL the windows,
they often need new rubber gaskets after years of sunlight exposure. UV
light kills rubber. Check that doors work properly. If they hang funny,
this can be a clue that structural problems are an issue.

After safety, draw up a floor plan. Make some scale drawings and cut
pieces out of construction paper, see if you might want to change the
layout.

The biggest upgrades would probably be the appliances and utilities.
Stove and fridge, air conditioning and heat, water supplies, sewer
lines, that sort of thing. Make an overall plan but schedule the work
so you can get it done in stages that make sense. Don't refinish a
floor in the front which you'll then track up when you refurbish the
back of the coach! The biggest payoff is for items of enduring value -
the kitchen and bath, just like any home.

Go online and check out what new coaches of similar size look like. See
if you can import some newer ideas into your unit.