You dont need any cruiseline offered excursion

Juneau - the shuttle to the Glacier is $7 per person one-way? I dont remember the exact amount, but the ticket booth is just a few hundred yards from the pier.

Skagway - the best thing to do is to have a rental car and drive to Whitehorse, Canada. You may be too late to book a rental car though as this is a very popular do-it-yourself excursion especially for a group of 4 to 5 persons.

Kitchekan - walk around town and go up to the park on the hill. It is too early for your time frame to see salmon run. The other worthwhile excursion would be floatplane sightseeing - that is a rather expensive excursion and carries inherent risk (small plane, potential of crash if weather changes suddenly).