I love that there's a museum dedicated to American art, founded at a time when American artists were underappreciated. The exhibitions are curated with a broad but discerning eye, and the architecture is spectacular. In my experience it's typically much quieter than the obvious choices like the Met and the MoMA - although both are remarkable, there's something I love about the scale and style of the Whitney.
I remember when I saw Shadows, by Andy Warhol in that big room. I was sitting in a sofa, and felt asleep. When I woke up it felt incredible. When my friends come to visit me it's a place where I like to go all together.