Can you name some novels in which numerous or large scenes are set in a library?

Wow, there are actually quite a few. Here are some of the ones I think are the most interesting:

The Name of the Rose by Umberto Eco

http://www.amazon.com/Name-Rose-including-Authors-...

The Time Traveller's Wife by Audrey Niffenegger

http://www.amazon.com/Time-Travelers-Wife-Audrey-N...

The Shadow of the Wind by Carlos Ruiz Zafon

http://www.amazon.com/Shadow-Wind-Carlos-Ruiz-Zaf%...

Fahrenheit 451 by Ray Bradbury

http://www.amazon.com/Fahrenheit-451-Ray-Bradbury/...

The Abhorsen Trilogy by Garth Nix

http://www.amazon.com/Abhorsen-Trilogy-Box-Set/dp/...

"The Library of Babel" by Jorge Luis Borges (a short story, not a novel, but one of the most memorable libraries in fiction)

http://www.amazon.com/Library-Babel-Jorge-Luis-Bor...

Possession by A.S. Byatt

http://www.amazon.com/Possession-S-Byatt/dp/067973...

The Archivist by Martha Cooley

http://www.amazon.com/Archivist-Novel-Martha-Coole...

The Club Dumas by Arturo Perez-Reverte

http://www.amazon.com/Club-Dumas-Arturo-Perez-Reve...

A Canticle for Leibowitz by Walter Miller

http://www.amazon.com/Canticle-Leibowitz-Walter-Mi...

One of these should fit the bill for you.

Cheers.

There is "True Believer" by Nicholas Sparks. The main character Lexie is a librarian, and the main male character spends a lot of time in the library doing research. It is part of a two book series, the second book is "At First Sight"

it's Merlin, my deer boy I hope your not looking through these books for spells now King Uther will have your head.

well I can say Harry Potter as they go to their library a few times

It -- Stephen King

Insomnia -- Stephen King

Incidentally, both library scenes are set in the same library.

Harry Potter... That's all that comes to mind.