Alaska or the Caribbean?

In the past when I've thought about going on a cruise, I always thought of a Caribbean cruise - somewhere I could get some sun and spend some time on gorgeous beaches. Since I've seen these gorgeous tabblos by JoanW of her cruise to Alaska, I think I've changed my mind. The scenery! Mountains, glaciers, wildlife. Scroll down, start with Part 1, and go through them all. She shared so many great photos from her trip that I'm starting to think that those other cruises would be a letdown.

What do you think? If you've been on a cruise, or more than one, what kind of cruise would you recommend? Because, one of these days, we are going on a cruise.