We went to the Cape Cod National Seashore and watched a movie on the formation of Cape Cod. It was pretty interesting. We learned that the cape was made from the glaciers of the last ice age. They deposited their rocks and silt there and it formed the 'arm'.
We stayed at a nice little inn in Chatham, which is a fun town. We went shopping and had wonderful meals.
We also stopped at Nauset beach, where when I was 10, I tried to body surf and was bowled under by the waves. They were very strong and powerful and it scared me.