Cruising Alaska is nice, just be certain to do it with a good cruise line.
My sister and her husband visited Alaska but not on a cruise. They had a wonderful time too. All but for the bit where the moose chased my sister.
John, you will love the seafood in Alaska. Those pristine waters do really make a difference. It was hard to choose between the halibut and crab! (So mostly we didn't. We ate one for lunch and one for dinner). :D