Crandon Park Beach is a real time commitment — fit it in only if it's a priority.
Allow Half to full day.
An ideal family beach — wide sand, calm shallow water protected by a sandbar, lifeguards, cabanas, and picnic facilities. The catch: it's on Key Biscayne so you'll pay the causeway toll and park fee, need a car, and it's a fairly plain beach without the South Beach scenery or scene.