Myself and my dad stayed in Cassa de Anna and it was great!
You cannot get a better location!
All the sites are within a walking distance even though the apartment is on a very quiet street it is right next to all the goings on of Palermo.
Giovanni gave us great recommendations for places to visit / eat.
We also used their friend (Giovanni) for some taxi transfers to beaches and the town of Cefalu, he was really helpful and a great person!
Small tip - order the taxi from Giovanni for your transfer to the apartment - we were bumped from a local taxi driver.
Overall great stay lots of space in the apartment and great hosts !