Anytime from May to September is a fine time to visit Alaska.  I'm partial
to fall- the tourists start to disappear, the weather is still fine, and
the fall colors on the tundra are spectacular.   A midsummer departure and
a September return would be just about perfect.  I made the trip up and
back in a month, using the ferry to save a few days, but recommend I'd
taking at least six or eight weeks if possible.

Denali National Park is my favorite place, not only in Alaska but in the
whole world.  To enjoy it, take some time to get off the park buses and
hike away from the road. Camp in some of the more remote campsites.   I
also highly recommend Valdez and Seward.  There are boat trips to see the
marine life in the Valdez and Seward areas that are out of this world.  I
have a website about my favorite places in the National Park system at
www.geocities.com/wdummitt.  It has writeups on Denali and Kenai Fijords
parks- these places should be part of any Alaska trip.  I wouldn't
recommend spending a lot of time in the Alaska cities such as Fairbanks or
Anchorage- outdoors is what Alaska is about. If your time and finances
permit, take a fly-in to a remote place such as Lake Clark or Katmai.  Most
of Alaska is not accessible by road and you should see some of the remote
parts of it if you have a chance.

The trip up can and should be as enjoyable as the time spent in Alaska. 
You can route your trip to include many spectacular places such as Jasper,
Banff, and Kluane parks in Canada.  I would recommend more remote and rough
Cassiar Highway rather than the Alaska Highway- much more scenic and less
traveled.  The Alaska highway actually is not terribly scenic.  Regardless
of which route you take, the roads will have many sections under
construction.  Be prepared for delays and make sure you have tools to do
minor repairs on your van.  I have a writeup on my trip from last year
which should be in the vanagon list archives- I'll pmail you a copy. I'll
be in Alaska again this July, although unfortunately not by Westy.  For
anyone wanting to visit the state but lacking the time to go by Westy, TWA
has some really good airfares available- I bought round trip tickets for
$500.    

Bill
St. Louis, MO