All the towns you'll stop in are quite small. Tons of shopping right at the docks. It's very easy to do your own walking tours if you're physically able.
In Juneau the Mt. Roberts tram is right next to the dock. So you wouldn't have to book that in advance if that's of interest to you. For $10 round trip to can take a bus to the Mendenhall glacier. I would suggest that too. The visitor center at the glacier has a small charge to visit. But there are many easy walks down to the water which are quite nice. Juneau is quite hilly but the as mentioned above you can get a map at the dock and walk to the museums and Russian church by using the map.
If you want to go whale watching or do an air tour than I would suggest booking in advance. You can do that directly and don't need to use the ship sources.
Ketchikan is also an easy walking town. 10 minutes to Creek street. Go up the funicular and walk down the married mans trail. All the shopping and the Lumberjack show arena are right there and an easy walk away. There is also a visitor center at the dock where you can book flight-seeing tours and the tours to the totem parks. There are totems in town and at the top of the funicular (in front of the hotel there). The salmon ladder is right by Creek street too.
Skagway is also right at the docks and walking distance from the ships. It'll depend on which dock the ship uses as to how much walking to get to town. I think Princess docks by the grafitti wall and that might require a tram or cab to easily get to town but it is walkable. White Pass Rail backs up to each dock there. You can book that in advance as well directly. Again there are visitor kiosks at the ships so you can book city tours etc. You can also get maps of the town.
In August the salmon will be running and you'll be able to see them in Ketchikan and Juneau. I can't recall seeing any in Skagway for some reason.
The only possible "problem" with going back to the ship for eating is if you have to tender. On our 3 cruises to Alaska we never saw a Princess ship tendering however. That takes some time to go back and forth to the ship however after the initial rush of people leaving the ships even the tenders aren't too much trouble.
You can't get lost walking around these towns. The ships are always in sight.
You're going to love it there........it's awsome up there!
