Half Moon Cay would be a perfect answer to the OPs question if it were nude beyond when BN cruises stop there. I mean, a nude beach with a pirate ship shaped bar right in the middle! With 2500 nudists on it. Our favorite nude cruise stop.
We were on that nude cruise that stoped in SXM so we had the inside info not to go to Orient that day. We met others that didnt know the BN ship was in that day and were glad they decided to pick that day to go on the nude speedboat cruise around the island. We met them again in June at Club O and all had a much more relaxing week. Willie the bartender remembered the day of the cruise but she didnt have fond memories of the experience.
Not sure about biggest crowd, but Little Beach on Maui, Hawaii was fairly busy. Much busier on the Saturday afternoon we were there but even the Tuesday we visited had substantial crowds. Still loved this beach very much.