If you are already booked, then you should be able to go onto your reservation and see what shore tours are available, and which ones match your interests and budget. Keep in mind some of these can run upwards of $250-$500 a person and can sell out fast.
What you can also do is use Google. In the search box enter something like "Top 10 things to do in Skagway". Some cities like Skagway, Juneau, and even Icy Strait will have at least a dozen or two different excursions.
I've cruised Alaska 5x, and am booked next year on a back-to-back (two cruises one after another). My interests are most definitely going to be different than yours. Some of the shore excursions that I have already booked are ones that others wouldn't at all be interested in.
😁