We were lucky to find a spot open in Nickerson State Park in mid August. We were pleasantly surprised with the privacy of our camp spot and how easy it was to get everywhere. There is plenty of great biking in the park and all around the Cape Cod area (rail trail!). The camp store was great for some last minute things we forgot, and there are easily accessible showers and restrooms with hot water (and very clean!). All in all, we had a fun time and it didn't seem super crowded even though the park was booked solid.