no need of day passes.
enter the bavaro beach aside the barcelo beach resort, entrance road shows signs "Jellyfish restaurant", great beach area, top calm water conditions, great food at that restaurant and cool drinks and hang out spots within walking distance(face water turn right and walk, nothing is far). the other spot is the above mentioned El Cortecito, beach area is smaller and by far not that nice prepared, but a lot of bars and restaurants around, also all in walking distance from there. an other great public beach area with very calm water and not crowded is in cabeza de toro, right in front of my vernada, just here you will noty find restaurants on the beach, just food to grab for to go at the local shops. an other good spot is Macao beach. when you enter that beach area drive to the right til the end, that little hut there looks like nothing but they serve the best seafood plates around, and for very reasonable rates, same for the beers. the owners name is "Vale", you can ask anybody there on the beach, they will point you out which one it is.
happy travel
Mike