Hello, we are a group of 4. We need to travel from Sorrento to Bari on May 25th. I'd like to drive so we can stop along the way at Herculaneum and other sites. We have all day. I have a few questions. Can I pick up a car in Sorrento? What agencies do you recommend? How difficult is the drive especially thru Naples? Is parking difficult in and around Herculaneum? Anything else I should know? Any favorites along this route? Thank you.
Honestly, given the location of Herculaneum, it would best be done by train from Sorrento during your stay. Bari is about a 4 hour drive, add in several hours, after their 8:30 open, does not leave much time for stops the rest of the trip.
There are big name rental agencies(Europcar, Hertz) in Sorrento, though as you mentioned, the first leg is a bit harrowing, but you may be able to take a route via modern Pompeii to avoid Naples city center. The bigger rental agencies would be easier to work with for a one way trip and dropoff.
As for what to see, the Greek temples at Paestum, near Sorrento might be a candidate, you could also route through the popular destination of Matera, but again, time is against you, for Matera, you might consider an overnight on the way. Otherwise, depending on the route, the area is mountains and pretty rugged territory, so scenic.
Might be easier to pick up the rental car in Naples after you have visited Herculaneum. Eliminate the bother of parking and possible car prowl with the temptation of you luggage possibly in view.
The major car rental agencies are in or near the Naples train station.
Depending on how long you are in Sorrento, it might be easier to do Herculaneum as a day trip, rather than on the day of your drive to Bari, to avoid dealing with bags, parking etc.