Family beach/lake experience

If you're looking for a quiet beach with stuff to do, I love Chincoteague Island and Assateague Island National Seashore. Make sure you visit outside of Pony Penning week, when it does get crowded and crazy. For the rest of the summer, Chincoteague is a town that's equipped for tourism yet small enough to bike around, with ice cream shops and an old fashioned movie theater. Nearby Assateague (where the beach is) stays relatively low-key because it's a National Seashore. The wild ponies that live there are an extra treat! There are several different websites for rentals (for once, I wouldn't recommend airbnb - not enough options available). I'd suggest getting a house on Little Oyster Bay. You're close to the center of town without being in town, and if you're confident in a canoe, it's an easy paddle across the channel. You might be able to catch the ponies having breakfast!