This is my firat time to the cape and looking to stay away from the tourist traps and eat where the locals eat

When are you going? That makes a big difference.

If you do a board search, you'll find lots of good information on Cape Cod -- attractions, food, etc. I've participated in some very detailed threads here. Also take a look through a guidebook for the area.

Beach - at least once it is worth the trip to National Seashore - Coast Guard Beach. (Named from an old coast Guard Station at the entrance). Have not been in a few years, but procedure is a bit tedious (unless it has changed) - drive to entrance in Eastham. There is a good sized parking lot about a mile from the beach from which they run shuttle trolleys to beach - lot gets full by late morning on hot days. Beach has lifeguards and some of the biggest waves on the Cape. Also bathrooms and showers. If you happen to have a National Parks Service pass it lets you park for free.

Last time I was there they allowed boogie boards but not floats - and boogie boards have to have a tether to attach it to the user. Bring snacks, drinks, lunch - there is nothing for sale. Soft, white sand that goes on for miles.

Another authentic thing to do is to walk some of the dunes around Truro - you can see them from the road - just make sure you park somewhere legal and follow signage about where you can and cannot walk - various nesting areas of endangered species of something.

Take a ride to Provincetown and walk to top of lighthouse. Warn the boys that Provincetown has an above-average percentage of gays who live and/or vacation there - great time for discussion of such thing - and if you discuss it ahead of time you and they will avoid any embarassing comments they may make. There is a marine salvage store - also souveniers and interesting junk - in Provinetown they would like. They used to sell cool stuff like inactivated old hand grenades.

Warning about seafood, including clams. Seafood has gotten quite expensive - if you find any cheap seafood, avoid it - but even bad seafood is expensive these days.

There is an Audobon Society wildlife/natural center in (not sure of town - maybe Brewster?) that has a nice boardwalk/nature hike.

Cape Cod Potato Chips has a factory in Hyannis that gives free tours and you get a bag of chips at the end.

Plan ahead for rainy day activities - Cape is wall-to-wall traffic jam during rainy days with everyone trying to find something for their bored kids to do.

Plus all the usual honky-tonk of arcades, etc - but you can find those on your own without trouble.