I have old friends in San Francisco who grudgingly tell me that the High Line is everything that's wrong with New York. Well, too bad. To me, it embodies a culture that's constantly reinventing itself: a defunct elevated railway that was becoming a burden to the city ("we used to climb up there to throw garbage bags full of rotting Korean food at the Hasids!", noted a successful photographer's assistant) becoming a startling example of urban greening for the public good. The expert landscaping makes it feel like walking on a Montauk beach - but a stone's throw from some of New York's most progressive galleries and hotels.
The jetties along Rockaway Beach are one of my regular destinations when I can get out there. I grew up in a Coast Guard family and spent a fair amount of time around the ocean and surfing. I still like to get in the water and this is the first Atlantic-exposed beach on Long Island as you start to get out of the city. When it comes to the environment, constructions like these can be contentious things but they also make for a series of interesting surf spots. Its got a lot of New York metro qualities you might expect including the Subway making its stops a couple of blocks back from the water.
For oysters & libations. The comprehensive oyster menu changes depending on what they can get that's fresh. If you know anything about oysters or just plain like them, this is without question the spot. Currently my favorite oyster (not always on their menu) is the Skookum.