RC, I did something very similar in 2014. After visiting Sicily, I flew from Sicily to Naples, then spent 3 nights in Naples and 4 nights in Sorrento, covering virtually the same places as you are, but in somewhat more time. You certainly can follow your suggested itinerary, although I think you will be somewhat rushing. From Sorrento, I visited Herculaneum, Oplontis and Pompeii on one day, on my own, by train. That was a bit much, and I found Oplontis to be the least exciting and made it too long a day. Try to avoid Pompeii in the mid-day and early afternoon, if it is a warm and sunny day. There is virtually no shade. I recommend joining one of the many 2-hour guided tours at the entry, where there are many guides hanging out, then poke around more on your own. No guide needed for Herculaneum, which is smaller. The ruins at Herculaneum are about a 10 minute walk, downhill, from the train station. I also did a day trip to Paestum from Naples, by train. The small museum next to the ruins at Paestum is excellent, with many pieces of art and artifacts from the ruins. Most memorable, the museum shows you what the temples would have looked like when in use 2500 years ago, very colorful and ornate, Totally different from today’s quite drab gray stones. But, the museum closes quite early some Mondays. The best light at the ruins is late afternoon. When I went I stopped for a couple of hours in Salerno on the way, and still had a nice morning walk and dinner in Naples, on either end of my day trip. Having just one day to visit Positano, Amalfi and Ravello will mean very little time in each, whether you are on a tour or using public transit. I did that too, with a group tour, but then had an additional day and spent about half a day in Amalfi, and half a day in Ravello, both worthwhile, traveling by public bus. The Amalfi Coast ferries are supposed to be a wonderful way to get around, if they are operating when you are there. Enjoy!