I drove tour bus for two years for those cruisetours. I would not recommend them. You'd be better off renting a car and putting together your own great trip. The TripAdvisor forums can be a great help: https://www.tripadvisor.com/ShowForum-g28923-i349-Alaska.html
Redeye Rides I believe operates year round. That would get you to Anchorage where you could rent vehicles: https://www.redeyeridesllc.com/
Here's the details on Denali after the summer season has ended: https://www.nps.gov/dena/planyourvisit/shoulder-season.htm
Here's the contact info for AvisAlaska's office in Skagway if you want to call and talk to them directly: https://www.avisalaska.com/locations/skagway/
You need clear skies to see the Northern Lights, and that's if there's aurora activity. Since your cruise is through a temperate rain forest, you chances for clear skies is low. If you want to see northern lights, fly to Fairbanks in early March
Watching whales from the cruise ship is like watching the big game from the very top row of the stadium. Being on a smaller whale watching boat is like being on the sidelines.
I can see Disneyland from the parking lot, but I'd rather get into the park and see it up close.
Just realize those tours do not actually go into the National Park.
To actually go into the Park, use the transit buses: https://www.nps.gov/dena/planyourvisit/shuttles.htm Although, depending on your exact dates, they may not be running yet.
I'm not a fan of the land tours offered by the cruise lines. And I think it's borderline criminal that they offer ones to Denali National Park before the buses into the park start running. It's just a desperate money grab.
My recommendation would be to cancel the land portion and book your own great trip using a rental car.
You can book directly with the White Pass & Yukon Route railroad now from their website. It does sell out, so I wouldn't wait until the dock: https://wpyr.com/excursions/
The Wingate by Wyndham is the closest to the rail depot: https://www.wyndhamhotels.com/wingate/anchorage-alaska/wingate-anchorage-downtown-ship-creek/overview
You wouldn't want to duplicate anything you'll be doing on the cruise tour. So what are you doing as part of that.
And, if you are seasoned travelers, I'd cancel the land portion of the tour and put together your own great trip with a rental car.