Fiumicino Airport

Not a good idea to book ahead one of the 2 direct trains after getting off a flight because you cannot predict if your flight will land on time or how long it will take to clear immigration. Just go to the airport train station and buy tickets when you arrive. If you hit it lucky, you may arrive in time to make one, Otherwise it is easy to get a frequent connection through one of the Rome stations, either Termini or Tiburtina, from the airport.

Just a little tip: When you get to the train station at FCO, there is no need to stand in a long line at the first set of ticket machines. Continue walking into the station where you will find many ticket machines with no line.

I would allow at least 45 minutes from arrival gate to train station at airport. Big concern is if your flight is late. We had about a two wait until the (11ish) train to Florence left the airport, but had espresso and a pastry in the cafe at the train station and the wait wasn’t bad.

Just to add on to the good advice above, and to also answer more of your original question: When you disembark from the airplane, you will walk several minutes to the first set of desks, immigration, where you will stand in a line that can be anywhere from five minutes to over an hour long. Next will be baggage retrieval (if you checked a bag) and then you will just walk through the customs "nothing to declare" doors into the main terminal. (Of course, if you have something to declare - food? - you will stop and deal with it before walking into the main terminal.) Once through the big sliding doors into the main terminal, you want to turn RIGHT down the terminal hallway. You will pass some shops, a small cafe, and some ATM machines on your right. In about 200 feet, you will see the sign to the train station on your left. Before you go through the doors to the train station, you will see the a ticket booth on your right. Don't stop there if there is any line. Proceed through the doors to the train station. You will go down some escalators, then up some more escalators to the station. Once in the station, there are multiple desks from which you can purchase your tickets. Some of the desks appear to be private transportation companies but they can sell you a ticket to Termini station. (I'm not sure if they can sell you the ticket to Florence SMN, but if they can't, the main ticket office in that station can do so.)

Are you coming off an international flight from the US or a domestic flight somewhere else in Europe. Checked luggage or not???? You have two big unknowns - flight arrival time and immigration (passport control) if on an international flight. Over the years we have gone through immigration is less than hour and one time it was over three hours -- it just depends. Even domestic flights can be a problem especially later in the day as flights tend to get behind for a variety of factors beyond your control. If it is an international flight I would allow at least four to five hour window. Or buy the ticket when you get there. That is probably the smarter move.

agreed with all above. also, you'll have to pass through immigration when you get to the airport too. when I went a few years ago, I did not prebuy my train tix. I took the free train from airport to the main station, then found a place to purchase my high speed rail tix to Firenze. the only part I found (traveling alone) was finding the bin (rail line).

also, make sure you are prepared to carry your bags on & off these trains. think of it like a large bus with high stairs etc. you will not be able to "roll on".

happy travels :)

.... took the free train from airport to the main station,...... You got damn lucky. It could have cost you 50 euro if were caught. There is NO free train from the airport to the Termini (main station).

Thanks to all for some very helpful advice! We will be arriving on an international flight from the US. It sounds like the station is a walking distance thing while negotiating some escalators and such and immigrations as well.
The reason I had asked this is from all I’ve read, the high speed trains require a reservation and I wanted to pick a feasible time. This is a Freeceargento high speed train with a time to Firenze SMN of 2:25. From all I’ve read in Steve’s book, reservations are a must for these trains. However, the base ticket class cost allows ticket changes up to an hour before departure. So I was going to book a train that gives me an hour and 53 minutes between flights arrival and train departure. Sounds like it may be hit or miss if that is enough time. Again, thanks to all who responded.

A ticket bought at the station includes a seat reservation. The chance of a train selling out is very small. But do as you see best.

Thanks Sam, sounds like it may be wiser to wait on a ticket purchase at the station to allow options and flexibility.

Coachhorne, I think you have figured i out correctly, you can buy the economy tickets ahead of time for your definite trains later in your trip, but its much easier to buy the airport tickets when you are completely ready to leave, as you don't want to add any more stress by nervously watching the clock to your already stressful arrival after a long flight.