Istanbul Memories and the City by Orhan Pamuk
"The Bastard of İstanbul" by Elif Shafak, gotta read that
Really, anything by Orhan Pamuk is good. I like Museum of Innocence. if you are a sci-fi lover, check out The dervish House by Ian McDonald, which is about a near-future besiktas.
If you are into history, I'd advise checking out A Peace to End all Peace by david Fromkin. It's about the end of the ottoman empire and World war 1, but it really sheds a lot of light about old Istanbul and the foundation of modern Turkey.
