Having lived at the base of Cape Cod, I have to remind myself to really appreciate it. It was too easy to take walks along the canal, eat fresh fish at the Lobster Trap in Sandwich, or head to Wellfleet when I needed a flea market fix. Route 6 and I were close friends - this is the main drag that delivers people all the way out to Provincetown and many points in between. One way to avoid taking Cape Cod's coast for granted is to visit by boat! You'll feel like you've earned every bit of it and not want to miss a thing.
I aim to highlight Falmouth and Hyannis because they are near mainland Massachusetts and have direct ferry service to Martha's Vineyard and Nantucket. Nothing against Yarmouth, Eastham, or Orleans, but I think Falmouth and Hyannis have a nice variety of amenities and offer an easy escape via ferry that many people would like if they're traveling by car or just want to leave their boats docked on the cape.
Falmouth is a lovely wooded town complete with shingled homes and independent stores. In the summer there are free outdoor concerts at the Harbor Band Shell (Scranton Avenue), and the weather is typically nice enough to enjoy the evening. There are several public beaches in Falmouth, as you're never far from the water. Try to squeeze in a sunset at Old Silver Beach or from a mooring at Quissett Harbor. Then get your morning caffeine at Coffee Obsession (110 Palmer Avenue).
Head to the enclave of Woods Hole, Falmouth's southernmost point, to catch the ferry to Martha's Vineyard (alternate departures to Oak Bluffs and Vineyard Haven). Woods Hole is home to a reputed oceanographic institute plus a handful of stores, restaurants, and bars. There is also a summer film fest with screenings at different establishments along the drawbridged main strip. Personally, the only thing I feel obliged to do is grab breakfast, lunch, or dessert from Pie in the Sky Bakery (10 Water Street).