Many of the attractions that you might hope to see offer very little in explanation or information for English speakers. It is a rarity to find English speaking tour guides through many of Palermo’s most favored attractions. You can hire professional and private tour guides for the city, but these can get very expensive. In fact, many of these services average 250€ for just an hour, and you are restricted to availability and scheduling.
Audio guides, on the other hand, give you all the information that you want in shorter bursts to allow you to experience more of the great city. Outside attractions such as Piazza Pretoria and Four Corners have little to no written information, so it is difficult for non-native speakers to understand the monuments.
Travel guide books only touch over Palermo and do not go into great detail, as there is so much to cover throughout Sicily. You will get all of the detail and nuance of Palermo with audio guides.