Basically a giant sandbox with a fringe of waves, the Cape and islands are ideal family vacation spots. A number of the larger hotels and motels offer deals whereby kids can share their parent's room for free. But beware of the fancier B&Bs: Although it's illegal for them to do so, some actively discriminate against children. The kinds that do are apt to be the kind that children dislike, so it's no great loss. For the most part, the local tourism industry is big on serving family needs, so there's not much you'll need to do by way of advance preparation.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.