Nice! I am sure you will be stopping in Juneau; Right in time for Kings which the season is on there. Juneau is tiny, there is like only 20 some miles of road, with easy access to the mouths of numerous creeks. Totally realistic to sneak off and fish for a day/few hours, etc if you wanna do the low budge route.
From the times I have visited my brother-in-law while he was stationed in Juneau for the Coast Guard, I used the local fly shop there, owner is Brad, they were very helpful. They also have a weekly fishing report
https://www.alaskaflyfishinggoods.com/juneau-fishing-reports/fishing-report-6-13-19 .
But honestly a lot of these spots are right off the road, super easy access.
As far as spots I like, Sheep Creek (Kings), Lena Cove (kings) , Echo Cove, Salmon Creek (Dollies), Peterson creek (steelhead, run is prolly over by now)
Some people in Juneau might mention you to go to false outer point on Douglas Island; Don't waste your time, it can be an absolute zoo for just a chance to catch a hatchery King.
Whatever route you choose, Have fun! and Don't forget to visit Alaska Brewing Company!