I was going to stay out of this thread but decided to jump in anyway.
Based on eight years of driving an '85 Westy and now a year and a half
with a '90 Westy I'll make these comments.
The engine and fuel system changes from '86 on make a far better driver
than the pre-'86.  An automatic transmission is not only easier to drive
but, in my opinion, gives better performance.  The automatic also gives
poorer gas mileage. If you are going to be making long trips, cruise
control is a must.  Even though cranky, A/C is very, very nice when
needed.  There are many nickel and dime improvements in the later years
(adjustable arm rests for one).  And the later years will probably have
fewer miles on them.  They also seem to hold their value a little
better.  One drawback of the later years:  VW started painting the tops
on the Westy's to match the body.  If a dark color this acts like a
giant heat sink in sunny weather.  Solution: paint the top white (not
the whole top, just the flat part on top).
Bottom line: Go with '86 or later, then condition is the major issue.