I'm not sure what the price difference would be, but I think the aft VA and
VB cabins would be superb for an Alaska cruise. The verandas are much larger and afford a magnificent view from the back of the ship. If your budget allows it, the SC corner suites on Zuiderdam are just awesome and would be perfect for Alaska. I'd book it soon, because I have a hunch that these are very popular cabins that sell off quickly in Alaska.
Tim