You need to look over a shore excursion list and narrow down your interests, there are a lot of choices. Myself I never book ship excursions, but I also would never consider just getting off the ship then deciding what to do. I highly recommend always having plans and reservations in advance. Very very easy to go independent in Alaska. If you miss the ship it will be your fault. Plan your tours for early in your port day. Take the recommendations of the tour operators. Don't skimp on tours, they are the highlight of traveling Alaska.