Apart from Dia Beacon, in Beacon (upstate New York about an hour away from Grand Central Station) and also the Judd Foundation in Soho, this institution is absolutely one of my favourite places to visit and it is located in Long Island City, Queens. It showcases sculpture in the broadest sense and has an incredible building that used to be a workshop that refurbished and fixed subway cars. It has been running since 1928 and when you visit you will definitely see why that is.
The Brooklyn Flea is another treasure trove of odd finds, cool artifacts, and handmade goodness. If you're looking for inspiration or just something cool to hang on your wall, you can probably find something here. And if all that treasure hunting leaves you hungry, you are in luck--there's a delicious assortment of local food vendors and artisans there too.