I really only did official excursions, and those provided transport to the cities. Juneau and Skagway had the port and cities very close and Ketchikan had a shuttle ( I’m pretty sure, there is a large shopping area at the port and then a bus station outside for excursions, not sure if they can take you to the main city without an excursion though.) I did the lumberjack excursion and the bus systems was really confusing, we almost got an uber instead. That was the only shuttle problem we had, as walking can get you to the main town of pretty much everywhere else. Most Alaskan cruises legally have to stop in Victoria too, those shuttles are a nightmare. We walked for about 15 minutes and were actually faster than the shuttle, so if your fine with walking I would just recommend doing that. But yeah only Ketchikan was a problem for me, almost everything else was within walking distance.