How to arrange transport from Rome international airport to hotel?

the most hassle-free way

have your hotel arrange to have a car meet you. Driver will be there with your name on a placard as you exit the secure area

Or just walk to the taxi queue, fixed rate of 48E for up to 4 people. And you don't have to worry about the sign guy if you are later or early.

Arrange a car - driver with a sign meets you at arrivals. You can do this through your hotel or through a service like romecabs (private car, not a cab) or rome shuttle limo (private car, not limo). I've paid about 50 (taxi is 48)

There are always taxis at the airport too. Sometimes there is a line, not too bad though. I just prefer to pre-arrange it if I'm paying nearly the same anyway.

If the hotel does not arrange transportation, any recommendations for car services?

I did have a car service arranged once for an arrival. The plane was LATE, and b/c I couldn't call them en route there was nobody there to meet me. Then when I called them, they told me it would be three hours for a driver to arrive. A licensed cab may be your best friend.

Is there any change to where to how to recognize a licensed cab driver in Rome?

It is a matter of travel style. We are just the opposite of Mira. It is just one less thing to worry about. Taxis are great in Rome and never hit a line of more than half dozen people. Two years ago, our flight was cancelled after a nearly six hour delay. It was enough of a hassle dealing with the hotel without dealing with a driver who was within three hours or so of picking us up.

I recommend Rome Cab Transfer for private pick up http://www.romecabtransfer.com/