I love books like this and will be checking back to see what suggestions you get and stealing them myself :) Unfortuntally, my baby-brain fog is making it difficult for me to come up with a full list of my favorites, but the ones I can think of are..

The Club Dumas by Arturo Perez-Reverte (Perhaps my very favorite "book about books" ever :)
The Rule of Four by Ian Caldwell
The Physick Book of Deliverance Dane by Catherine Howe
The Egyptologist by Arthur Phillips (A very clever book where the reader is challenged to figure out the "real" story from a series of contradictary accounts. But it was so unbearably depressing to me that I was unable to finish it :(
I know some of the Preston and Child Pendergast novels give me that same sort of quest/"we must find the right book to save the day!" sort of feel to them, but I'm not sure if they would give quite the same vibe to everyone else... There is a minor character called Wren who is a book-restorer who shows up in a few of those books.

I'm going to have to look back through my reading journals as my mind is just blanking right now.