The train ride in Skagway is the White Pass Railroad. This is a must-do for this port. The scenery is spectacular and extremely exciting. There are several different excursinos that take you on the RR, and they're all good. We took a bus thru the White Pass into the Yukon, and then took the train back to to Skagway. That was one of our better excursions.
Like Kevin said, Juneau has great whale watching, and a drive-up glacier. . We combined the two. There is excursions that take you Whale Watching , then drop you off at the glacier before going back to the ship. Leave time to walk thru Juneau. Very nice little town.
Ketchikan is a nice walking town, but there are also good fishing excursions from there. Also some grat float plane and helicopter excursions.
In Victoria, go and see the gardens. They are amazing.