Fraunces Tavern is a historic tavern with a bar, booths, and nooks where you can sit and have a drink. You can take a wander through the joint and look at the cool things to look at, as the whole place is a museum.
It might feel a little weird to visit just for a drink, but you can't actually go just for one drink - Mr. Tavern, first name Fraunces, mandated that.