Hiking is excellent everywhere in Alaska. Perhaps consider going on your own in some areas- even hook up with someone on the ship.

Easy areas- Skagway- Lower and Upper Dewey Lake- trailhead between 3-4 ave at the train tracks. Juneau- East Loop trail 3 1/2 miles, need to get to Mendenhall glacier, ultimate cheapness

, take the city bus, stop is on Franklin St. down and across from the Red Dog. Drop off is 1+ level mile from the visitor center, verify return times as the bus doesn't run that often. Or take the glacier shuttle $10 RT. Trail head is behind the visitor center. In Ketchikan- it is walkable to the Deer Mt trail but far better is the Preserverence trail out by Ward lake which requires a car. Consider renting from Alaska car rental, they used to allow dock drop off, inquire. Also each of the cities have walking tour maps and are a worthwhile activity.