The best way to enjoy Manhattan is from Brooklyn. Transmitter Park offers views without the crowds, and you can pick up coffee-to-go and treats from nearby Ovenly. The India St/Greenpoint Ferry is a 5 minute walk and will take you all the way to the Rockaways in the Summertime.
The New York Earth Room is an interior sculpture by the artist Walter de Maria that has been installed in a loft at 141 Wooster Street since 1977. Go see!
I can’t get enough of the dioramas, but my favorite parts of the AMNH are the Halls of Meteorites and Minerals. There are some beautiful specimens here, and best of all you can actually lay your hands on the 4.5-billion-year-old Cape York Meteorite.