When hailing a cab in Palermo, the best thing to do would be to ask at the reception of your hotel about the approx. fares. And when you enter the taxi - ask the driver about the fare to your destination. Note that some of the meters run fast and you should negotiate the price before the trip begins.

It should be also said that trying to hail a cab in town by simply flagging one down won't work. You'll need to walk over to the nearesr taxi rank, and you'll find them at the Politeama, the Massimo Theater, the central train station, in Piazza Indipendenza in front of Bar Santoro and parked outside upscale hotels.