This excursion with this company should be at the top of your Juneau list. The Mendenhall Glacier portion of the excursion was interesting. We had a great bus driver who provided good background on the area and the glacier. The glacier area was beautiful, clean, and had a few park rangers available to explain what you were seeing.
The whale watching was simply incredible. Captain Sarah and Naturalist Katie were very professional, fun, and great guides. Sarah got us out to the whales quickly and we saw a bunch of spouting, a few tail fins, and a bunch of whales near the surface. A humpback breached and that would have made the excursion...until we saw a mother humpback and her calf breach simultaneously. Then the mother and the calf put on a show by slapping the fins on the water's surface and breaching individually five or six more times.
The whale watching portion of this excursion quickly became my favorite vacation memory of all time. I was fortunate to experience it with my wife and adult children plus some friends who happened to be our on boat.
The double breach was so extraordinary that I've run out of superlatives when describing it to people back home.
Book this excursion and ask for Captain Sarah and Katie.