I just got back from the cruise. Skagway, no question is White Pass Railroad, really stunning. My recommendation is to go up and back on the railroad. They will make you change sides at the top and the left side going up is better, so if you take the latest tour in the afternoon up and back, it is unlikely to be as full, and you may be able to stay on the same side of the train as did we. I can't describe fully how spectacular that scenery was but it was breathtaking.
In Ketchikan, don't miss the Great Alaskan Lumberjack show which is great entertainment. Slightly cheesy, but well done and good fun. The guys in it are terrific and the woman who is the hostess is very funny as are the guys.