Calling all travelers!!!

Recently, Nick and I have been tossing around ideas about where to go on our honeymoon. Our top places are Ireland and Greece, but we've decided they're going to have to wait a few years. (We're actually talking about maybe doing Ireland in 2010 after he runs the London marathon!) So we've shifted our thinking to places that are a little closer to home (translated: North America and, hopefully, more affordable). Right now, we're leaning towards an Alaskan cruise. What I'm wondering is... Have any of you been on a cruise through Alaska? (I know Jeff & Sarah have been there, but can't remember if it was on a cruise or not??) Can anyone who's been there give us any suggestions? Thoughts? Insight? Which ports of call should we make sure the cruise includes? Which could we pass on? What cruise lines are better than others? Should we do a 7 day cruise? Longer? Any advice/help would be appreciated! Thanks guys!!