For Cape Cod Boston, decide on one for a 3 days stop. If Cape Cod, the KOA in Moddleboro is fine, or even Maple Park in Wareham. On Cape Cod is Cape Cod Camp and Resort in Falmouth.
If Boston, Minuteman or Normandy Farms are both close to rail stops with easy access to Boston. Do not try to drive into Boston. Terrible traffic, rudest drivers and propane restrictions in the tunnels.
Saugerties has a nice KOA and Rip Van Winkle park. We've stayed at the KOA but not Rip. I looked at Rip and it looked like it would be fun for kids.
