I think it takes place every Saturday morning to afternoon, vintage shopping while having a great view at the Manhattan skyline from the East River State park. You will find lots of vintage shops and warehouses around this area of Williamsburg.

Why not 

This botanical garden is massive. If you like to be surrounded by foliage, bring a picnic on a nice day.

I love sneaking over here in the middle of the day to see a movie - they always have the best selection of films. I recently saw Pina in 3D and The Kid with a Bike here, and another time I saw Bela Fleck play the banjo after a screening of Throw Down Your Heart.

Daytime café, nighttime bar. Nothing stronger than 30-proof. Delicious beer and really good wine. Kind people run & staff the place. The garden in the Summer is perfect. I make near-daily visits.