Tranquil, idyllic, empty Assateague Island, with its National Park seal of approval, pristine beaches, and wild ponies, is oddly adjacent to Ocean City. Just head back to Route 50 and make a left on MD-611/Stephen Decatur Hwy, and follow it around to the Park entrance 15 min drive.
The Delaware beach resorts to the north offer a more relaxed environment than the bustle of 'O.C.'. Straight up the coastal highway, US-1, is Bethany Beach 30 minutes and Rehoboth Beach 45 minutes.
A 50 minute drive west along Route 50 will take you to Salisbury, the largest city on the Eastern Shore, with a quaint historic center.