I have just published a trip report for the cruise to Alaska that our family went on in June of 2007. Our family of four, along with my husband's parents, embarked on a 7 day northbound cruise on the Diamond Princess followed by a 5 day cruise tour that went as far north as Fairbanks. At the time of our cruise Katie was 10 and Emma was a couple of weeks shy of her 4th birthday.
Our entire extended family had a wonderful vacation. Sailing along the Alaskan wilderness coastline and viewing glaciers, icebergs, whales and other wildlife is simply breathtaking and traveling by rail into the interior of the state gives one a sense of just how vast and remote the Alaskan frontier still is. The kids were thrilled to see all sorts of wildlife, however, the highlight for them was interacting with every single sled dog that they came across during our 12 days in Alaska. Alaska is definitely a destination that I would recommend trying to see with your kids before they grow up.