Re: A family day... what do sailors do?
My son - then about 8 - recruited random kids from other boats to play hide-and-seek and I found kids in the chain locker, in the hanging locker, behind the sails in the quarter berth, and a few other places. I had no idea there were so many hiding places.
Kids + dinghy + dogs = fun.
Here is a hint - Do NOT overthink it with "are you bored are you scared are you sick OMFG we better go back". Self confidence - Here is what we are doing it is safe and fun goes a long way. Find a place the kids can get off the boat and explore. Looking for turtles, crabs, and interesting driftwood was always fun.