I used to visit a college friend that lived in Chatham (see "elbow" of cape cod).
Cute little town if you're into that girly shopping stuff

It's got its own decent share of history to check out.
His parents knew some folks that had some beach front property and they'd drive their tiny camper out to it right on the sand.
We'd take their small boat out and meet up with them, anchor it not too far away and then camp with them on the beach. It was really nice.
I'm not sure about the public beach situation there though.
The only real touristy thing I ever did on the cape was go to P-town. you park up by the school on the hill and just basically do some walking around, shopping, eating, etc.
Oh and there's a pretty cool tower at the top of the hill.
It's a LOT of stairs, but still fun.
(oh yeah and cross-dressers. that part is a real hoot)