When the restaurants no longer require an hour wait and Cape Cod takes on its next season, you can enjoy Provincetown without the crowds,
Whale watching is good through October and this should not be missed. You can take off from several different places: Hyannis, Provincetown, Plymouth, Boston but although the ride may be variable in length, sooner or later you will wind up at the Stellwagen Sanctuary where the whales hang out.
The Cape Cod National Seashore, created by JFK in 1961, is made up of beaches throughout Cape Cod; they are open year round and autumn is a good time to take wildlife walks–you can spot seals, watch birds, stroll the shoreline, and visit lighthouses.
On a rainy day, everyone–and I mean everyone–congregates at the Sandwich Glass Museum, a surprisingly comprehensive and varied museum, carrying everything from classic pressed glass originals (you can see copies sold in the Met Museum),
Many restaurants have their own oyster beds and if you are a fan, they are cheap here.Plus, there are lots of little towns to visit all over the cape and you can find good deals at hotels when all the tourists (everybody but you) leave. All in all, a pleasant, slightly out-of-high-season trip for the fall.