I would say that Holland America Line (HAL) would be worth considering. They do have plenty of kids on board for the summer Alaska cruises, and they do have a kids club. The main pool has a sliding roof over it so you can use it even if it gets cold or rainy, which is really common in Alaska. HAL has the most ships going to Alaska each year, and they are one of the few lines that goes to Glacier Bay (though not on every trip). Some of their cruises actually have the whole ship going into Tracy Arm and some just drop people off for a separate excursion, but all of their Alaska cruises go to a major glacier, either Glacier Bay, Tracy Arm or Hubbard. They do a lot of cruises out of Vancouver, BC, which uses a more scenic route with calmer waters, up the inside of Vancouver Island.
One area where they're lacking compared to Disney is family activities. They really don't offer activities for the whole family per se. They have a variety of kids activities divided into age groups, through the Club HAL program, and separate activities for adults. Kids are welcome to come to pretty much any adult activity if they're interested, but how many kids want to learn to fold towel animals or watch a cooking demonstration? I felt basically the same way about RCCL; on the ship we took (Enchantment OTS) they had kids activities and adult activities, but no real family activities like family trivia, family bingo, family game shows, etc.
When we last went on a HAL cruise, our kids were teenagers, and they basically went to a few activities with us, but otherwise did their own thing. Mostly they read or watched movies on the interactive TV system.
