Not sure if this should count as a park. It's basically the lovely plaza where you can take the 1-2-3 lines at 72nd Street. There are 2 newsstands, some stone benches, some plantings and occasionally a sculpture or artist will show up.
It's a pleasant space in a pleasant neighborhood. In warm times, beware the rodents at night. They'll bounce off your shoes without so much as blinking.
Open space, open all hours (sort of)
It's just a plaza
Haagen Dasz, Jacques Torres, Gray's Papaya, American Museum of Natural History, Central Park, Riverside Park, Fairway Supermarket, Levain Bakery