I too have a preference for Glacier Bay, superior overall scenery since you travel the fjord over 50 miles. You generally see 4 glaciers, sometimes more. Wildlife is more viewable since it is narrow. I've seen brown bears several times, moose once.
The reference above for the humpbacks is Point Adolphus, it's a toss up if your ship will go out of the way to view, some do, some don't. Best for this area is a port stop in Hoonah and a private whale watch. Key for a desire of viewing is to be out on deck when sailing Icy Strait. If coming from Skagway, often the ships are stalled out waiting for escort into Glacier Bay, plenty of time for whale watching. Last year had a repeating breeching plus several other on the May trip. On the August trip, the cpt. did sail up to Point Adolphus and spent about 45 min with bubble net feeding, lunge feeding etc.