Randall’s Island sits in the East River between Manhattan, the Bronx, and Queens. On Labor Day weekend, that geography becomes the stage — three days of electronic music where the New York City skyline is visible from the festival grounds in every direction. What does Electric Zoo feel like? It feels like New York — specifically, like New York choosing to dance. The island setting is unlike any other festival in the country: surrounded by river water on all sides, skyline visible in every direction, the city audible in the silence between sets. The stages run from afternoon into the early morning, and the crowd spans every age group, every …