To have the best lunches like a 'fried peanut butter sandwich', lounge or book a room for a few days in the heart of the city, visit 'The Ace Hotel'. Ease down in the couches, order a Brooklyn Beer and relax. A great place to meet up.
Having the experience of owning and running a coral reef aquarium (and frequenting this particular shop about once a week) - I was sad to hear it closed it's doors. Their reef display tank was always amazing. These pictures were taken from PetCo at Union Square (I also used to go there for my saltwater needs).
A street party/DJ sound system built out of a shipping container. A little slab of hungover berlin/pregaming Berlin in Brooklyn. Whomever the great DJs in town are you will find them playing a low-key set here for a crowd of less than 50 people. Sunset is magic as there's a straight shot through to Manhattan and the light is perfection.