You can see the schedule at
http://www.ferroviedellostato.it/fer...il/inglese.jsp

There are at least two trains an hour during most of the day.

Guidebooks are often full of misinformation. Maybe they mean that you have to have a seat reservation, which is true in certain classes of train, but if it is required, it is automatically included in any ticket you buy in Italy.

I have been successful purchasing tickets on Trenitalia using my Citibank MC. I use the citibank 'virtual card number' feature (see their website). This generates a new card # with limited expiration date so I don't have to use my real card # on the internet.

If you are a citibank customer, check it out. If you are not, ask your issuing bank if they have a similar identity theft option.

Great info and so quick, love this!!

You can buy all your train tickets at the airport when you arrive. Allow enough time to get to the station. The Leonardo Express runs every 30 minutes and travel time to Roma Termini train station takes about 30 minutes. You will also need to allow time to get from your train to find the other one. You will probably want to allow enough time at Termini to buy some drinks/lunch to take with you on the train.

Purchasing AV or ES in advance online will be a bit of a gamble if your flight is delayed (most are these days) or if it takes a long time to get your luggage.

As far as the security code they are asking for, it's that 3-digit number on the back of your credit card. Lots of places are asking for that now.

While I'm all for buying your tickets ahead of time, I think the exception is when you're taking a train immediately following a flight. As you say, if your flight is late, you will have to change the reservation. I think it's a lot easier to buy the ticket after you arrive than to have to change one you bought ahead of time.

I ended up having problems buying on the trenitalia website also. Kybourbon, I see that you said you can purchase train tickets at the airport. I'm flying into Venice. Do you know if I can purchase my train tickets at the Venice airport and if so, where? Thanks

You can purchase train tickets at FCO at its train station. This was suggested because the posters were heading immediately to Naples. Some people might make the mistake of standing in line to buy the ticket from FCO to Roma Termini, and then stand in line again at Termini to buy the ticket to Naples.

Venice airport has no train station. I'm not sure if the counters where you can purchase local Venice transport tickets also sells train tickets. If you don't need to use the tickets immediately (I'm sure you're arriving and then staying in Venice a few days . . .), just go from the airport to your hotel in Venice. Get your tickets at Venice SL or a local travel agent in Venice.

I don't know if you've decided to book first class or second but a few years ago I took the Venice train from Rome and booked first class. I was traveling alone so the difference in cost wasn't much and there was more space availble in the compartment and in the car in general. There were only three other passengers in my compartment so there was space for luggage on the seats for a 20-22 inch suitcase. When I walked down the car to the lav I noticed empty compartments and many empty seats. Of course, it doesn't mean the same thing would happen when you go but I was glad that I'd paid the bit extra for first.

There was also a huge difference in the queue getting onto the first class car and the rest.