Well, mid Cape is very touristy, etc. but you might want to try Dennis, but on the Bay side/Rt.6A. Nice beaches and a bit quieter. If you want a place where you can walk to town, then Chatham is your best bet. Osterville also has a nice little downtown area, but again, it's busy in the summer.
We always stay in B and Bs. It's a lot more economical.
One thing you should do is the hike out of the trails of the MA Audubon center in Wellfleet. If the tide is right, you can hike 6-7 miles.