Went on Spirit years ago, cruise was great, it was Inside Passage. It was great for our first Alaska cruise, but if I were to do it a second time, and could afford it, I'd go for a longer cruise and one that took you to more places. Some excursions have a hefty price, but where else can you view glaciers from the air, walk on one, do dog sled rides etc. Bring your cash or credit card, but it's worth it.
I think Alaska cannot be defined.