I've booked for a week in Ischia in May and due to flight prices wanted to add on 3 days somewhere. Sorrento was a possible but doesn't make me hugely excited, but Naples seems to have lots to do, food great etc. I know the traffic is terrifying, I've seen it before. Has anyone done the underground tour? We've been to Pompeii and Vesuvius before. Might do Pompeii again, but would like to visit Herculaneum, which seems quite quick by train.