Amalfi Coast

In season there are also boats. Or you can go from Salerno to Pompeii by train and walk or take taxi to Circumvesuviana railroad station in Pompeii and go by train to Sorrento. But that's a detour. And of course buses.

Some ferry lines are scheduled to start on April 1, but some don't begin until mid-April or May. There are SITA buses all year long from Sorrento via Positano to Amalfi and from Amalfi to Salerno. There's also a bus between Amalfi and Ravello. If you want a scenic ride, that's the way to go if you don't have a ferry. It's also likely that you'd have to change ferries in Positano or Amalfi between Sorrento and Salerno. Sorrento to Amalfi is scheduled at 1.5 hours and Amalfi to Salerno at 1.25 hours.

Your other option seems to be to take the Circumvesuviana train from Sorrento to Pompeii, then either walk or take a taxi to the "real" train station about a mile away for a train to Salerno. Each leg is about 1/2 hour on the train.

We are sleeping in Salerno from the 4th to the 5th, doing the Amalfi Coast, and sleeping in Naples on the night of the 5th to the 6th.

You can take the train from Napoli Centrale (or Roma Termini if that's your starting point) to Salerno and take the bus to Sorrento.

This works if you are going to see some of the Amalfi Coast on the way to Salerno, otherwise it's lots of backtracking.

You can also take ferries from Salerno in season.

Is this the same trip that has 1.5 days in Paris, followed by a train to southern France? You have a whirlwind of travel, with a few tiny sightseeing opportunities, most of them while waiting to check your baggage at most tourist sites, assuming they have baggage check.

If you have not locked yourself in yet, I want to suggest that you can improve this leg of the trip. There is nothing wrong with Salerno, but NO ONE is going to ask you, back home, "if you saw Salerno." Why have you scheduled this big loop? Is it because you think it's more direct from Rome to the A.C.? Or is it because you cannot bear to omit a single town on the entire Amalfi Coast, in the 9 hours of daylight you have scheduled to see it? Even with a private car and driver, it's not that easy to negotiate the entire Amalfi Coast. You cannot see its hidden treasures in the amount of time you have. You can only scratch the surface.

Do yourself a favor and see only Positano. When your train gets to Naples, go downstairs and take the Circumvesuviana commuter train to Sorrento, leave your bag at the hotel baggage room (assuming your room is not ready) and take the SITA bus to Positano. If you insist, do Amalfi as well.

if you train to Salerno, you could take the Travelmar ferry, which starts April 1st, weather permitting. Depending on the time you arrive in Salerno, on your first day you could take it to Amalfi, then bus to Ravello.
Bus back to Salerno.

On day 2 with your luggage, (?) ferry to Positano bus to Sorrento, train, Circumvesuvian,to Naples.

After though here. Leave your suitcases at Napoli Centrales'left luggage and just take an overnight bag for your 1 night stay in Salerno.

Spend your time on the coast. Why go to Sorrento at all?