This is what we did in 2005,
We flew into Anchorage, rented a car and had hotel reservations in Anchorage, Denali, Fairbanks, GlenAllen and back in Anchorage. This took one week.
We spent a few days in Anchorage before taking the Carnival transfer to Whittier and cruising for another week down to Vancouver.
We have a special needs child, so the train was not an option. We require the flexibility that auto transportation afforded us.
Loved the West side of Alaska. Anchorage to Denali to Fairbanks was great. Loved the East side from Anchorage to milemarker 101 just past Palmer.
The Fairbanks to GlenAllen part we would never do again.
The highlight of the trip was walking on a glacier at milemarker 101 (East of Palmer) Sorry I can not spell the name of the glacier but you can't miss it. For a total of $30.00, we literally drove and parked right at the glacier. We followed a well marked trail (that changes daily) out onto the ice. You can walk quite a distance (to the picnic table) without special equipment. This was particularly wonderful because it was something our special needs son could do.
You can also rent the riggings and hire a guide if you want to go UP higher on the glacier. Of course that was not an option for us. But just walking on the glacier itself was amazing.
We can't do a lot of "excursions" because of his limitations....so this gave us an "experience" to bring back with us to share from our Alaskan trip.