Train from FCO to Navona area?
 

Evening, While doing some searching for our upcoming trip to Italy, I am confused as to what train would be better (from the airport) to get to our destination on Via del Pellegrino. I thought the train to the Termini (LE) and than a cab or bus to the apartment, but I see there is a train, FMI, that will go to a Trastevere station. Would this be a better choice? Thank you for your help!

Either would be suitable. There is a taxi rank outside Trastevere station, and the station itself is served by regular commuter train every 20 min or so from the airport. Also the fare is less than Leonardo Express to Termini.

The train to Trastevere is a local commuter train that I would advise against if you would be using it during rush hours and could afford the extra 6E for the Leonardo Express to Termini. Taxi from either station would be in the 10E range for your destination, bus or tram 1E.

bookmarking

By the time you pay for the train--and a taxi to the hotel--you can book a shuttle service---door to door. See www.airportshuttle.it

Airport Shuttle is 35€ for 1 person and 6€ for each additional person. The train from FCO to Trastevere is 5.50€ per person and then you would need taxi/tram. The train departs about every 15 minutes and travel time is 25 minutes.

Rome Shuttle Limousine is cheaper than Airport Shuttle (40€ for 1-3 people - 50€ for 5).
http://www.romeshuttlelimousine.com/FiumicinoE.htm

I think Roma S. Pietro station is a bit closer to your destination than Trastevere, but would involve a train change at Trastevere and you would still need a bus/tram/taxi the rest of the way.

Via del Pellegrino is just off Campo de' Fiori, so I wouldn't want to use the Roma S. Pietro station. For more than one person, you're usually not going to spend much more for a shuttle that will drop you door to door, as bob mentioned.