There are no direct flights from Naples to Florence, you will have to change in Rome and it takes about 3h 30 mins...
By train, you can catch the Circumvesuviana train (suburban service) (http://www.vesuviana.it/inv/a62.pdf) which takes about 1h 5mins. to Napoli Garibaldi (which is the subway station of Napoli Centrale). There you change to a Trenitalia-train.
ES (EuroStar) trains, which are the fastest trains only need 3:36 for Naples-Florence and are much cheaper (even in first class) than flying... so catch a train, it's easier, faster and less stressful!
... and you save the environment by using a train :-)
Thank you Robbi - what website can I use to book the EuroStar? RailEurope.com
No! Definately not Raileurope, they will charge you a much higher fare!
Nearly all trains in Italy are provided by Trenitalia (former State Railways):
ES (Eurostar Italia) is their high end product followed by ICplus (Intercity), EC (Eurocity... same like IC but goes abroad), IR (InterRegionale)....
Go to www.trenitalia.it --> English on right top of page
You can buy your ticket online (Naples-Florence), you print your confirmation, that's it... just show it to the conductor. You can buy your ticket also at Naples station (not Sorrento, as the train Sorrento-Naples is private run) or for a little fee at a travel agency.
The fare Napoli Centrale - Firenze SMN is € 42,35 in 2nd class, € 63,01 in 1st class. (raileurope quotes USD 67 = € 54,63 2nd class + shipping fees). As Sorrento - Napoli Garibaldi (subway station of Napoli Centrale) is a commuter train, get your ticket just before you go.
Robbi - you've been most helpful. One more quick question (2 parts) - are the first class seats reserved? Since I'll be on my honeymoon I'd obviously liked to sit next to my wife. Should I book the tickets soon or wait unitl I arrive in Italy? Your help and detail is greatly appreciated!!!!!!!
Eurostar bookings include a free reservation (in 1st and 2nd class) and you are not allowed to board the train without reservation.
If you know when to go, just buy your tickets online at www.trenitalia.it (switch off your pop-up blocker). It generally should not be a problem to buy a ticket just before you go, but most crowds go on Friday and Sunday...
Train travel is something very usual in Europe, most people (me too) do not plan it days before, they just get a ticket before they go.
Buy your tickets online or when you arrive... all the best to you and your wife!