Hi eb! We did the Princess 12 day Voyage of the Glaciers land/cruisetour in May 2008. We flew into Anchorage and took the land tour from there. The cruise was southbound.
We debated about the Fairbanks option. After talking to a couple of people who had been there, they said we wouldn't miss anything if we skipped it and that's what we did.
We really liked Anchorage and hope to return there some day. However, if we had it to do over again, I think we would have opted for the longer tour and gone to Fairbanks. The reason? Because since we have been home, we have seen so many things on TV about Alaska and Fairbanks is mentioned often. It would have nice to have experienced it and been able to say "we've been there".
If there is a way to see Anchorage AND Fairbanks, that would be nice.
Whatever you decide, you will love it.
With Princess, a nature tour (Tundra Wilderness Tour) was included in the price. This was at Denali Lodge. It was a great tour. We saw bear, caribou, moose, etc. We did not take any other excursions at McKinley Lodge or Denali Lodge. The scenery and surroundings were so pretty, that we just enjoyed them. Across the street from the Denali Princess Lodge is a little strip mall with souvenir shops. We spent a couple of hours there, too.
I'm sure the excursions from the ship are the same whether you are north or south bound, but I could be wrong.
Hope this helps!