Italy Trip - September 2018

Depends if you're planning on having a car. We have done it both ways and prefer NOT to rent a car, 1= it takes more time than you realize to pick up and drop off a car, 2=Parking is hard most everywhere, 3=we prefer not to drive, 4=the train is SO easy.
Last time we spent 3 wks in Italy (Venice, Florence, Rome, Sorrento) without a car and it was our favorite trip ever to Italy.
Venice & Florence are our favorites. We stay in Florence extra days to take day trips into Tuscany (2 day trips give a great feel for the area). While we have stayed in Positano, we much preferred basing out of Sorrento- and taking guided day trips from Sorrento to Positano, Capri, and Herculaneum (Sorrento is an incredible Italian town, easy to get to from Rome, and some of the best food in Italy). I don't recommend driving the Amalfi Area- it's too tiny, narrow, curvy - and you will want to pay attention to the amazing views while someone else is driving. I know I didn't really answer your question, but am interested in how others recommend you do this - we are returning next year, (although we may not repeat this area since we've seen in twice and there is so much me we want to see in Italy). Feel free to PM me if you want any of my recommendations (we have had amazing experiences using day trip companies in italy). You will have a wonderful time. Happy Planning.

The easiest would likely be the train to Salerno, then the ferry to Positano. Or buses from Salerno.

There is a ferry between Positano and Capri. Where are you going after Capri?

Assuming you fly in and out of Rome, the correct sequence of events is the following:
Land at Rome Fiumicino (FCO)
Immediately take a train from the airport to Florence (two trains at 11:08 and 15:08 go directly from the airport, all others, every 30 min, require a change at Roma Termini or Roma Tiburtina)
After Florence take a high speed train from Florence to Salerno. Then from Salerno take a boat to Positano. You can also take a bus to Positano (with a bus change at Amalfi), but I think the boat is more beautiful (weather permitting).
From Positano to Capri there are boats, both regular service and also private Day boat excursions. Depending on how many days you have available I would recommend to stay based in Positano the whole time and visit Capri from there for a day, which is more than sufficient. If you really want to visit. Apri more, you can take two boat excursions in two different days. Positano is also a good base to visit other places in the area, such as: Amalfi, Ravello, Sorrento, Pompeii, even Naples. The first 3 by bus, the last two by bus to Sorrento then by commuter train from Sorrento.

After visiting Positano you would go back to Rome (bus or boat to Salerno then train) for the remainder of the trip before flying home.

The point is you should leave your departure city (I imagine Rome) as the last destination of your itinerary).

Thank you for all of your input. We are flying in/out of Rome. The itinerary is Rome - Florence (2 days), Positano (3 days), Capri (2 days) then back to Rome for a day prior to departure.
It definitely sounds as if Florence to Salerno via train then either boat or bus to Positano is the best option from what I can ascertain.
Any other recommendations and advice is also appreciated.

How many nights are you actually there?

If its just 7 days ( 6 nights?) you are spreading yourselves pretty thin

No, we have 2 days on each end in Rome.

I am curious to know where the ferry from Positano to Capri docks? We are staying in the Marina Grande area on Capri. I have yet to find any definitive answers on whether the ferries dock in Marina Grande or Piccola Marina. Does anyone know the answer.