The TDC has a library that’s rather nice. There’s also a Taschen store and a nice selection of design titles can be found at the MoMA bookstore. The various school libraries may have weird summer hours, so call ahead for those.

Otherwise the New York bookstores aren’t very special, they’re just bigger and more expensive versions of the bookstores found everywhere else. New Yorkers rave to me about the gigantic Strand Books (which isn’t much bigger than a large suburban Barnes and Noble), but it’s really just a huge clearing house for remainders and discounted bombs dressed up with some stacks of discounted new stuff, and the rare books room is mix of junk and esoterica, almost none of which is of use to typographers. Don’t waste time there if you have serious research to get done. If you’re looking for special antique stuff I have the address of a by-appointment only place that does type