I've been on 5 cruises and one was to Alaska (roundtrip from Seattle). Alaska was our favorite. We went on Princess and that was our favorite cruise line (have also been on Carnival and Royal Caribbean).
The Alaskan scenery was fantastic. To me it was like Yosemite on steroids. We also saw lots of humpback whales, orca, eagles, bears, etc. We are considering on going on another Alaskan cruise in August.