I don't know how off the beaten path it is but when my wife and I visited Hadrian's Villa six years ago, we had the entire place to ourselves. I loved it but my wife found the experience of being alone in those ruins too eerie. To get there, we took the train from Rome to Tivoli and then took a bus to Hadrian's Villa.
Also noticed someone mentioned Viareggio earlier. I've never been there but I remember from my English Lit classes that was where Percy Bysshe Shelley washed ashore after drowning in the Tyrrhenian Sea. He was also cremated right on the beach at Viareggio.