Here's an article from USAToday in which Rebecca Miller of Library Journal magazine shares ten of her favorite library locations.
I am sad to say that I have only visited one of these ten; the New York Public Library. I have always wanted to visit the Library of Congress, but on my one and only trip to Washington, D.C. I passed on a couple of places I hoped to visit in deference to wanting my children to see other historical sites and the Library of Congress was one of those places on which I passed. I'm sure that some day I will get back there and if so I plan to spend as much time as I am able wandering through the Thomas Jefferson Building.
But I can see that I would love to visit ALL of the other libraries on Ms. Miller's list and hopefully my personal or work-related travels will take me to each of them.