Rome Taxi

In Rome, the train from the airport is a "recommended" way to get downtown, however, you may find that for two persons, a taxi is a preferrable way to go.  When you consider the train fares, schedule, taxi  fare from Terminus, and the train hassles, you may want to consider hailing a cab.  Cabs are less stressful after a long transoceanic flight; they are reasonable and comfortable.
The train is about 11 EUR per person. 
A taxi from Fiumicino is a 40 EUR  and 30 EUR from Ciampino, this is a set fare day or night - don't let them charge you more (they will try). Perhaps rather late now but, for a map of the area covered by the set airport fares, see...
http://www.comune.roma.it/was/reposit...

(Some changes - including an increase of 5 Euro to both rates - are set to take effect, apparently, on 31st October 2010)  ....................................
Once you arrive in town, you can decide how to get to the attractions.  You should find Rome easy to walk EVERYWHERE.  You get to see more, meander in and out of shops, and it is no more than 45-50 minutes to any attraction you will want to see in major downtown areas.  You do need good shoes as the brick or cobblestone streets are tough on your feet and legs.
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Should you feel you've been cheated by one of the licenced taxis, the link for the English version of the Rome Comune's official complaint form is...

http://www.comune.roma.it/was/reposit...

There are some explanatory notes on the Italian version, intended to assist in the identification of the offending vehicle and its driver - roughly, they translate as.....

1 TAXI licence number
Shown on the vehicle's front doors (near the symbol of the Comune of Rome) and also on notices beside the numberplate on the rear of the vehicle and affixed to the inside of the left rear passenger's door.

2 Name of the driver
Shown, together with the TAXI licence number, on the notice affixed to the inside of the left passenger door (in some cases, instead of a person's name, that of the relevant taxi cooperative is shown)

3 Radio Taxi company
The Radio Taxi firms operating in Rome are as follows: 3570 Radiotaxi - 6645 Prontotaxi - 4994 La Capitale - 4157 Tevere - 8822 Eurocosmo - 5551 Samarcanda - 5601646 Ostia Lido

4 Radio Taxi abbreviation
Varies depending by Radio Taxi company, but a name (an Italian or foregin city, country, river, star or gemstone) followed by a number