Yes it is an older crowd. My kids saw lots of people their own age in the gym the first morning and thought to themselves "hey, there are tons of our own people on this ship," and later that night, realized they were all performers for the cruiseline LOL. There were many multigeneraltional families with large tables in the dining room and on deck. But overall, DH and I were some of the younger people on the ship, and we are in our 50s.
Food was good, I don't know about "the best." There were some hits and some misses, I would not say any of the included dining stood out as great. We did have some delicious specialty meals.
In terms of having fun on the ship, this is so subjective and depends very much upon individual needs and expectations. Honestly, we were there to spend the week together as a family. We all loved it! We were on the Nieuw Amsterdam, which has a BB King's Blues club, which we swung by almost every night for some live music and some cocktails. We went to the headliner shows each night and found them at least somewhat entertaining (not going to compare with DCL). We are also people who entertain ourselves, so we enjoy simple pleasures like doing puzzles in the lounge on the upper deck, and watching the wildlife and scenery from our verandah. We booked excursions that appealed to all of us and they were amazing, but we booked those independently, so you can do that regardless of cruiseline.
Bottom line is, we don't regret having chosen HAL and would do it again in a heartbeat. Honestly, our only regret is that we didn't book a land/sea cruise starting in Fairbanks and embarking in Anchorage. We didn't have the time or money at the time to do that, and now I don't know when we will have an opportunity to go back.
All that said, I understand your worry about the older crowd. Princess might be a nice option for your family. We were going back and forth between Princess and HAL. We chose HAL based on a small boat glacier viewing excursion they offered in Juneau. (We ended up not doing that excursion after all, as we found a more active excursion that was more appealing to the kids.)