FCO to Termini Rome, Leonardo Express

It is the best method (IMO) and certainly the quickest as there are no traffic concerns. A few points to mention though....

• there are two trains servicing FCO, the L.E. and the FM-1. Be sure you board the correct train!
• you can easily buy tickets (€14 PP) at the airport station, either from a Kiosk or from a staffed ticket office (cost may be higher at the staffed office).
• you MUST validate (time & date stamp) your ticket prior to boarding the train or risk a hefty fine starting at €50 PP, which will be collected on the spot!

"Is there any reason anybody wouldn't use this?"

1. A taxi from FCO to central Rome is fixed at €48. For several people, it can be the same price or cheaper to take a taxi. And you get door-to-door service, which some people want or need (particularly on a first visit, or if they have heavy luggage).
2. This is particularly true if your hotel is not close to Termini, and so you plan to take a taxi from Termini to the hotel. In that case, the LE plus taxi would actually cost more, particularly for 3 or 4 people, than a fixed rate taxi from the airport.
3. On the other hand, it's not the cheapest way into town either. There are several bus companies, charging €4.50-8.

Otherwise, the Leonardo Express works very well.

Here's a post from Ron In Rome, detailing all the options and the pros and cons of each: http://www.roninrome.com/transportation/transportation-options-from-fiumicino-airport-fco-to-the-city-of-rome

The last two times in Rome, we stayed in the Trastevere, the FM1 to Trastevere station, then the Tram gets me to my hotel quicker, cheaper and less crowds than the express-to-Termini-then-Bus/taxi

Same thing works if you are staying near Largo Agentina or Campo di Fiori as the tram ends at the largo.

If you are specifically going to Termini (to catch a train elsewhere) then it is "best" based on ease and is your only train option (the FM1 does not stop there), but as mentioned above Taxi or Bus can be a cheaper option.

Thanks for the replies guys.

It's my wife and I, and our hotel is about 2-3 blocks from Termini.

I bought my Leonardo Express ticket at a shop at FCO that sold dolls, stuffed toys, and other souvenirs. Usually I buy train tickets at newspaper/magazine, map, and souvenir stands. But I got drawn into that shop and she sold train tickets too.

Anyway as you walk up to the tracks, just ask the RR Attendants standing around if the train on the tracks is the Leonardo Express. And there is always a RR attendant standing at the Validator Box at the entry to the LE track. Just give your ticket to him and he will validate it for you, then return it to you.

I've used the buses others have mentioned and they're another good option. Buses take about 25 minutes longer but cost only 5 euro, and I think the scenery is more interesting. You'll catch glimpses of E.U.R., San Giovanni in Laterano and one of the Roman city gates along the way. Note that some buses stop at the Ostiense train station first, so don't get off there. Terravision buses arrive on the far side of Termini while the others arrive closer to the hotels, but along a busier street. In November, the windows to purchase bus tickets had been moved outside near the bus stop, but they may now be back inside if the remodeling is finished. To get to the bus stop at FCO, exit after you pass the train station entrance and go right once outside.