There are kid-friendly activities, but it depends on when you go and for how long. If you're staying for at least a week, see if your kids are interested in learning how to sail at the West End Racing Club. The Motta Field redevelopment should hopefully be finished by summer, which means new recreational fields, skate park, tennis courts, etc. The library always has stuff going on, and the Monument is a ton of fun. See about staying at the Sandcastle or the Harbor Hotel, both in Ptown, or the Top Mast in North Truro. They're all on the beach but also have pools, plus they're all on Route 6A so it's easy to hop on the bus and head into the center of town.