The Pirate Adventure Cruise. This would just be for your son, not with your husband because it is kids only. It is for 4 - 12 year olds. They take place daily and are from 9:30 - 11:30, departing from either the Grand Floridian, Beach/Yacht Club, Caribbean Beach Resort, or POR. We looked in to doing but have not done it yet. I've heard good things about the pirate adventure cruise on this board.
I don't know what they have that a father and son could do together that would be special. Maybe the Pirate Fireworks Cruise? They seem to have more things for girls.