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.
This is the rooftop of my building. I come up here daily with my dog or friends to get 'fresh' air, see what's happening in the streets, or to catch sunsets and the occasional sunrise. My landlord has been trying for months to put a stop to our rooftop access, but every attempt he has made thus far has been futile.
You've heard about the reading room at the New York Public Library, haven't you? Then I need not go on. Just look at it. And you're allowed to hang around in there!
Spoonbill and Sugartown Booksellers is in a pretty visible spot at 218 Bedford Avenue in the Williamsburg neighborhood. I still can’t help but point it out as one of my favorite places to check out books, especially arts related publications. Needless to say its an easy place to stop by with plenty of things to see in the immediate area.