Hey Ron -
We took 3 months for the entire trip -- about 6 weeks in Alaska. including a week and a half in Denali (the furtherest you can drive to, dry camping for one week, and more modern for 4 days. It took 24 days (kind of liesurely from here DE to Whitehorse, YT (which I HIGHLY recommend), via the Trans Canada Hwy. Instead of returning right away, we went down the OR coast & visited my daughter in CA, which added 3 weeks. In all, when you retire, DO THE TRIP!!! I've learned enough about you on this forum (and seeing you in Glacier NP) that you will love it. As was said, Provincial parks in Canada are wonderful, as well as those in Alaska.
Jack