I'm going to be the Debbie Downer here. Last year I took a 14-day Alaskan cruise on the Noordam. It was the last cruise of the season, and visited some ports HAL usually doesn't have on their itineraries - Kodiak, Valdez, and Prince Rupert. Of the 6 Alaskan cruises I've taken, it was my least favorite.
There were very few ship excursions offered in Kodiak, Valdez, and Prince Rupert, and no local or private operators the days we were there. In Kodiak, the local merchants didn't even know there was going to be a ship in port that day until they saw us walking into town. The visitor's center was open and seemed glad to see us and had some information for those interested in hiking and other outdoor activities. We were in Valdez before anything opened, except for the grocery store. Just walked around the cruise terminal in Prince Rupert and went to the library to use their internet service.
Even in the usual suspect ports of Ketchikan, Skagway, and Sitka, a lot of businesses were already closed for the season. I love Sitka and know my way around, but there was literally horizontal, blinding rain that day, and I ended up returning to the ship so I could get out of my soaking wet clothing. The highlight of the whole cruise for me was the tour I booked in Skagway thru HAL up to the White Pass Summit. We rode in a bus with a retired geologist as our tour guide. A very scenic and informative experience. In Ketchikan there were still a couple of operators offering tours so I was able to do something besides shop and walk around town.
I guess what I'm saying is to keep expectations low. One of the Great Bear Rainforest cruises being offered is at the very beginning of the season and the other is at the very end. Be aware that there may be limited tourist infrastructure at the less frequently visited ports. My cruise itinerary looked good on paper, but I wouldn't pay to do it again.