The outer Cape from Eastham north to Provincetown is part of the National Seashore with beautiful cliffed beaches. There's a National Seashore Visitor Center off of Route 6 in Eastham that has the information you need to make your plans. There's also a salt pond trail from the Visitor Center that's an easy hike.
Nauset Beach in Orleans is also very pretty and you don't have to climb down a steep cliff to get on the beach. If you want to view the Atlantic from a cliffed beach, good suggestions are Marconi Beach and White Crest Beach, both in Wellfleet. Marconi Beach is the site of the first trans-Atlantic wireless communication. Highland Light in Truro is also a beautiful place to stop and has a golf course next to it.
As Ron mentioned, Provincetown at the tip of the Cape is fun, but this time of year the selection of restaurants will be down quite a bit.
Chatham at the elbow of the Cape is still pretty much open for business this time of year. There's a Coast Guard station and light house that's very accessible on Shore Road at the end of Main Street. It's a great place to get a look at the famous Chatham sand bar and learn about the rescue of the wreck of the Pendleton. The movie "Finest Hours" was about the amazing rescue of crew of the wreck. Many places to stay and eat in Chatham. I would recommend the Chatham Squire restaurant as a good choice.
Hyannis is the largest village on the Cape with many restaurants and places to stay this time of year. And ferries from the harbor run daily to Nantucket and Martha's Vineyard.
Falmouth is also a large town with places to stay and eat. The Woods Hole village of Falmouth is picturesque and has ferry service to Martha's Vineyard.
Sandwich, not too far over the Sagamore Bridge, has the Heritage Museum and Garden's. It's a good take on day that the weather isn't great.
If you want a taste of old Cape Cod and have time for a slow drive, get on route 6A in Sandwich and take it all the way to Brewster. Very pretty and lots of antique shops if you like that sort of thing.
Virtually any decent place you go for dinner will offer lobster and a raw bar with oysters and cherry stone clams.
Best wishes for a great trip!
