Dia:Beacon is a short train ride from the city in a former Nabisco box printing factory. This art foundation has 240,000 square feet of art from the 1960s to the present. Dia features the work of Sol LeWitt, Imi Knoebel, Andy Warhol, Dan Flavin, Agnes Martin, On Kawara, Bruce Nauman, and many others. I love going during the summer to enjoy the gardens surronding the building.
If you're far up in Greenpoint and need caffeine + snack, Bakeri is my spot (I say "bake-ery", others say "bach-ery"—I still vote the former). Known for their baked goods—both savory and sweet—it's the perfect spot for a coffee meeting, small breakfast, or a solo book read. There's one large communal table in the center, plus a few two-tops and decent counter space—one of the rare cafes with enough room that it's rarely packed (except saturday!).