I always start by going to tourism website in each port
then finding some idea WHAT is offered there,,and some guides to check out.Can contact references and never pay up front.Then when you see some tour,,check it out on you tube to see if there.
My hubby did the kayak with whales in Juneau,,but didn t SEE any,,oh well,,he had fun.But was cold and wet.They do give waterproof gear,but be prepared for that.
We did several glacier tours ,but with cruise excursion.Felt a time constraint in some ports and went with safe option.
Also, get a few guidebooks from library to give you more ideas,,or purchase them to bring with you(or kindle etc).
No matter what you chose,,have fun.