Alaska is REALLY awesome. I cant make a comparison to anywhere else though. I hear it all depends on what cruise line you go with. I heard Carnival isnt that great. Ive heard Royal Carribbean and Holland America are good, and I can vouch for Princess
There are a lot of older people on Princess, and I think the same is true of Holland America, however, there were quite a few teenagers, and I met some really cool people. I would definitely say that you should go to alaska if you get the chance, it is absolutely amazing, all the glaciers, the mountains, the forests, everything is just really cool. The one downside is the weather isnt always that great. When I went it was in the 80's every day except one, which it was pouring, which is really unusual.
Cory