We're taking the South of Italy tour in September and I'm looking for a recommended reading list
Not a book but a movie.
Purple Noon with Alain Delon filmed in Naples, the Amalfi Coast and Rome. The location for a good chunk of the movie is a fictitious town based on Positano.
Try novels by Elena Ferrante and Domenico Starnone (rumored to be the same person or spouses).
I enjoyed all of these before our trip to Rome:
https://a.co/d/7cK593M The Secrets of Rome: Love and Death in the Eternal City
https://a.co/d/9HtoIqe Four Seasons in Rome
https://a.co/d/fk2Vxna Basilica: The Splendor and the Scandal: Building St. Peter's