First and foremost, anything in the Dave Robicheaux mystery series by the amazing James Lee Burke. For my money, JLB is not only the best living mystery writer, but he is one of the best writers writing, period. Dave Robicheaux is a complex character, the likes of which we rarely see in the genre anymore. If you haven't experienced the wonder of JLB, I suggest beginning with Heaven's Prisoners, the book that started my love affair with Robicheaux. The descriptions of New Orleans are incredibly vivid and will be the perfect introduction to this complex and beautiful city.
For the historical romance lovers out there, I highly recommend Candice Proctor's atmospheric and suspenseful, Midnight Confessions. Proctor is one of the best and the NOLA setting, combined with a dash of suspense and a passionate romance combine to make reading this book an enjoyable visit to New Orleans in the late 1800s.
My favorite romantic suspense writer, Linda Howard has two books that feature New Orleans and both are well worth a visit. After the Night is one of Howard's most popular books and features a rather remarkeable Alpha male hero. We all know that no one writes an Alpha like Linda Howard and Gray Rouillard is one of her most memorable. After the Night has an incredibly steamy gothic tone and features some of the hottest love scenes LH has ever penned. Kill and Tell is also an excellent read, with more of a nod toward the espionage aspects of Howard's suspense writing. Both are a whole lot of fun.
So, there are a few titles to get you in the mood for a NOLA visit. I could go on and on with this list since writers have found New Orleans to be a fascinating setting for their novels, no matter what their genre might be. Since very few places have the complexity, history, beauty and just sheer quirkiness of NOLA, I'm sure it will continue to serve those writers well,