In Juneau, I'd plan on a whale watching excursion. You can go with a ship excursion or a private tour company. I'll be going on Capt. Larry next month, Orca enterprises if you want to check them out.
Just be sure to read through all the tours and see what you really want to do. Yea, most of them are on the expensive side, but when will you get a chance to do that kind of thing again?