I always try to avoid booking excursions through the cruise line unless I absolutely have to so these are my recommendations.
https://alaskashoreexcursions.com/ is a good place to book a lot of Alaska excursions.
Juneau: https://www.harvandmarvs-juneau-whale-watching.com/ fantastic company with small boats so you can get closer and get there faster. We saw so many whales.
Be prepared with a backup if you plan to do a helicopter tour. They get cancelled a lot because of weather. (Ours was cancelled in July so we did the sky tram and we paid for a tour to Mendenhall Glacier at one of the booths by the sky tram. It ended up being a great day and saved us a ton of money when we were refunded from our helicopter tour)
Skagway: https://chilkootcharters.com/ (similar to excursions offered by the cruise line, but better--less
people is always better!)
Ketchikan: the town is great to just walk around and we love to eat at The Alaska Fish Company. This trip
we also did the Lumberjack show (
https://alaskanlumberjackshow.com/), which was fun (I recommend booking it on your own unless your ship is docking far away. It is literally a couple blocks from the dock.) Our first time to Ketchikan I booked a canoe trip through the cruise line that was very expensive and totally not worth it. I wouldn't recommend it.
Victoria: I don't think Princess is there long enough to really do anything. We were there from 11-6 so had
time for something. If you do, I recommend
https://www.atasteofvictoriafoodtours.com/ this was a fantastic excursion of food, history, interesting information, sights, etc.