Singing Beach in Manchester-by-the-Sea. The drawback is you pay for parking in town then schlep your way to the beach, though it's a nice walk. Magnolia has Black Beach, but I know nothing about it. Devereux Beach in Marblehead (not technically Cape Ann, but hey it's close enough) has paid parking at the beach, but the beach isn't as nice as Singing. Marblehead also has Preston Beach, which is nicer but you have to hope the tide is right for the day you visit. Manchester and Marblehead are nice day trips with plenty to see and do. Either place isn't going to be the Cape Cod beach experience, so keep expectations appropriately scaled. Further afield is Hampton Beach, NH, north but beyond Green Head territory. This is more the boardwalk-type beach experience. It's been 35+ years since I last visited there, so I can't say much about the current scene. But back in the day one would expect to see plenty of teens, families, and Canadian vacationers.