Why does it matter if it is a single building or multiple buildings? My university has a library that has book space, quiet study areas, group study areas and multiple overpriced food/drink vendors.
I'm also thinking that you might not want lots of food and drink around the stacks of books. But in an open study area, why not?
Finally, if I go to the library to look at stacks of books, the last thing I want is for the bookcases to be surrounded by a somewhat noisy study area with groups of people talking. It should be as quiet as a tomb.