My husband and I are sailing on Spirit Aug 13, 2008, from Vancouver to Whittier. We booked our own land option afterwards. One day in Anchorage, followed by the domed train to Denali, hiking and rafting in Denali for 2 days, the bus back to Anchorage and flying out of Anchorage.
I used a company called Alaska Tour and Travel to book all of our land extras, and found them to be very affordable (I shopped other lines' CruiseTours). It really wasn't a lot of extra work and you can customize your trip.