I think if we get a big library to explore it'll be in Ishgard or Sharlayan. Sure the Thaumaturge guild has an extensive library but I don't think it would offer what Sharlayan would have, especially if there are more books by Lewphon. I'd like to see complete copies of "The Five Ages - An Eorzean Chronology" and the "Divine Chronicles" by Mezaya Thousand Eyes.