Coastal Living magazine won’t reveal the winner of its “Happiest Seaside Town 2013” contest until May 10. But it could be Harwich Port, one of seven villages in this Cape Cod town, and one of 10 finalists in the magazine’s survey. What makes Harwich happy? Beaches, restaurants, nature trails, fishing — they’re all here. The town’s historical heart is Harwich Center, a picture-postcard New England landscape with a park, church spire, and old, well-maintained houses. But the action is in the Port, with restaurants and shops, outdoor entertainment in summer, and side streets leading straight to the beach. Harwich has a lot to offer families, and spring is a great time to enjoy off-season rates and a little extra elbow room.