Best contemporary art museum in NY, have to take a train that goes along the Hudson river (best views during fall season!) / rent a car. This museum only uses natural light, and has pieces from Richard Serra, Judd, Sol Lewitt, Walter de Maria, Robert Smithson, Flavin, all best of the best!
My second-favorite outdoor-place in Manhattan. The abandoned 1.6 km rail tracks running above Chelsea down to the Meatpacking district were turned into an above-ground park. Perfectly nice place for sitting in the sun, reading, relaxing, having lunch in some green spot in the city. Nice views at the Hudson River, New Jersey, the Statue of Liberty (little small from there but still visible) and the architecture around Chelsea.
This place is amazing. It's a short walk from our apartment and has an amazing happy hour including cheap guacamole and $4 margaritas. We can spend an hour or five hours here at a time because the environment is so casual, welcoming, and the food is just damn good. Get the lengua or the camaron al mojo de ajo tacos or hongos and rajas con papas if you are vegan.