We were in Juneau in September and did the "on your own" Jeep tour through the ship. The jeep had a tablet that provide direction to a number of stops, including Mendenhall, and had narration along the way. We were able to spend as much or as little time as we wanted at each programmed stop (and made a few side stops of our own). We just had to have the Jeep back by a certain time.
In ISP we didn't have a planned tour but decided to take the tram to the top of the hill and did a free guided nature walk there. There's a place at the port where tours can be booked on site, but go when the ship docks, as they fill quickly.
