New Orleans is a checkerboard town with safe and dangerous blocks often adjacent to each other. Stay on the busy streets, especially at night. Even when in the French Quarter, stay with the crowds. Men can wear very lightweight sport coats, tie, and light cotton slacks. Don't be surprised if the company presidents greet you wearing a short-sleeve dress shirt and tie, with no jacket.
Business women can, in most cases, leave the dark power suit at home.
Remember, too, that even formal business lunches may be held in extremely informal settings. K-Paul's, Commander's Palace, Nola Restaurant, Mulate's Cajun Restaurant, Emeril's and Brennan's for brunch. The Moonwalk, the Riverwalk, St. Charles Avenue.