Im a wide angle junkie but Alaska is a BIG place, especially from a cruise ship. You'll quickly find that your shots have just too much water in them using wide angles from the boat. The wildlife and sheer size of the place lend themselves very well to telephoto lenses. Of course, it's a different story if you're going to get out and hike trails a bit - then a wide angle becomes more useful, but it doesnt sound like that's in your itinerary.
I would bring your 24-105 and either the 70-200 with 2x converter or get your hands on a used/rented 100-400. You can pick up the latter used and sell it when you return if you wont need it and not be out any more than shipping costs, this is what I would do.
If you need something for lower light, bring your 50 1.4 or pick up a used 430 EX II.