Nauticus has a lot to offer. But unfortunately, I think they want children to attend, but there isn't much for them to do. They seem to be trying to get more child oriented exhibits, but there is not nearly enough to keep a child's attention for too long. The Battleship Wisconsin is a very neat place to visit, but you are waiting in lines, and paying additional money to see that also.
I did like the Imax theater and I really enjoyed their exhibit on Natural Disasters. But again, for an adult this is a great place to go, but for children, they will lose interest rather quickly. If you are retired military, I think you would especially enjoy their exhibits.