You could also try the Sandwich Motor Lodge, They have suites with sliders that open to the pool. It would be easily accesible to Plymouth and the Cape. It is on 6a, Take exit 1, after the Sagamore Bridge, Right off the exit straight onto 6a, Its up on the hill on your right. If several people stayed there it would be easy to have a party poolside(indoors). There are already tables and chairs set up there. 508-888-2275, Also The Cape Codder resort in Hyannis has an indoor wave pool and 2 waterslides!! 508-771-3000. That would be exit 6, take a right off the exit, onto route 132, you will come upon the Cape Codder on your right. Of the 2 I maybe would say the Cape Codder?