We cruised to Alaska on
DCL in May 2019 with a then 3 year old and 7 year old. We did private shore excursions as much as possible because I didn't want to be stuck on a group bus tour with a little one having a meltdown or getting carsick, etc.
Vancouver: Capilano Suspension Bridge Park, Breakfast with Bears on Grouse Mountain, Rented bikes with toddler trailer to bike around Stanley Park, visited aquarium, Flying over Canada (little one was too short so took turns with eldest)
Glacier Day: DCL Glacier Explorer excursion, took turns to save paying for kids who would have whined about the cold the whole time anyway. Spouse went on first boat, I went on second.
Skagway: Rented Green jeeps and drove to Tutshi Sled Dog camp for sled dog ride and gold panning. They both took a short nap on the drive back to the ship, then after lunch we took a Temsco helicopter to a glacier for Glacier Walk excursion.
Juneau: Whale watching tour on the Scania with Captain Alan (google Adventures in Alaska charters) Ended up being a private charter because no one else booked that day.
Ketchikan: Float plane to the Misty Fjords
I recommend grabbing first seating at dinner if you can. Many nights my little one was so tuckered out he fell asleep before dessert. My eldest absolutely adored the kids clubs. No idea how things might change with the clubs post-covid, but it was hard to pull him out. With Character meets, check the schedule and show up at the designated spot before the character appears, drawing a huge line. This will save you a long wait, especially for the characters in their Alaska outfits on Glacier Day. We only went to the Frozen stage show and I think it's not to be missed. We also signed up in advance for the Frozen character greeting and the Character breakfast, both were really fun.