The AS (Airport shuttle), mentioned by Rick near the end of his Roma chapter of the 2009 Italy book (Phone: 39-06-4201-3469) may be a good choice if you have an early flight.
Also nice for those of us who think there should be an alternative to high taxi prices, especially if you're traveling alone and can't share the cost with fellow passengers, and for those who just don't want to schlep baggage through public transportation.
I was charged 25 euro(cash only)for a 4:15 am pick-up, no extra charges for my 2 bags. The driver even stopped at Castel Sant'Angelo and in front of the Vatican for passengers to take photos of the floodlit sites.
I just printed a page from their web site (www.airportshuttle.it.)with the phone number on it and asked my hotel to make the reservation for me.
Am I the only one that would be annoyed if on a shuttle to the airport the driver made additional stops for passengers to take pictures of sights?
At 4:15am just take me to the airport or let me sleep another 15 minutes!
There were only 3 of us in the vehicle besides the driver, we were all going to the same terminal and everyone was in agreement that we'd like to stop, particularly since another set of passengers had cancelled at the last minute, and there was extra time. The driver accommodated his passengers and got us to our destination in plenty of time. The two stops were about a minute or two each and were on the way.
I find no fault in this. Sometimes its better to appreciate than to complain.
Sonia