I didn't cruise in Alaska, but there are so many things to do inland that it's well worth planning a day or two just for that if you can. If you can do more than 2 days, a trip to Denali is well worth it--it is GORGEOUS! And you can do all sorts of activities--horeseback riding, visits to the sled-dog kennels, a busride to Mt. McKinley (well, 24 miles away, but it's still awesome
Of course just being in and around Anchorage and seeing the sights, the stunning flower displays, and the occasional moose is really wonderful! Unfortunately we never made it to Seward. The wildfires were so bad that year that even 30 miles away, it smelled like a huge BBQ and the smoke burned our eyes.