Joanna - Here is a list of 15 (count 'em, 15!!) flightseeing outfits in Ketchikan:
http://www.visit-ketchikan.com/TravelersDirectory/tabid/71/Default.aspx
Oops, editing to point out that to get the list of floatplane operators, you have to click on the "Flightseeing" item in the "Tours/Sightseeing" item on the left side of the screen.
And here is the website for a flightseeing outfit in Juneau:
http://www.wingsairways.com/

It might be useful for your friends to telephone or email these little companies to get an idea of availability. Bear in mind that the day we are in Ketchikan, there will be four (aarruugghh!!) large ships there - RCCL Serenade of the Seas (2,100+ passengers), NCL Norwegian Star (2,200+), HAL Veendam (1,300+), and HAL Westerdam (1,850+). Thus, there will be a lot of competition for the services of these small flightseeing operations.

On our day in Juneau, the only other large ship is the Carnivore Spirit (2,100+ wet-T-shirt-contest-loving passengers).

All things considered, your friends may want to do a bit of advance planning. Otherwise, they may be spending the days in Ketchikan and Juneau visiting the local Starbucks.

Cheers, Fred