Any advice from you seasoned travelers on the best way to get to Positano from Rome. Do we buy train tickets upon arrival or purchase in the US? What website should I use to purchase tickets if you suggest buying in the US< Thanks for your help.
Buy your tickets when you get to Italy. Take a Trenitalia train from Rome to Naples. Take the private Circumvesuviana train from Naples to Sorrento. Take a Sita bus from Sorrento to Positano. See here: http://tinyurl.com/38jero.
I would be very tempted to take the Hydrofoil from Naples to Positano instead of the bus.
I suppose an alternate route might be to continue on the train to Salerno, then take boat or bus up the coast to Positano. One less change and you avoid Naples, but it may be longer.
We took the bus from Sorrento to Positano and took the ferry back - very relaxing compared to the winding bus ride! If you have time, you should go a little further north to Amalfi and then back to Positano.