I stayed at Alessandro's place with my family (we're 4). The apartment is great, located in an old beautiful palazzo at literally the center of the city. Greatly equipped and comfortable. Only detail: the living room gets hot and the fan wasn't enough during the night, so sleeping in the sofa bed might be a little hot during summer. Besides that, everything was perfect (the view from the balcony is great!).
Alessandro was great too. Gave us maps, recommendations (follow them, the places we visited to eat and have drinks were great) and left some water and juice for us. He waited for us upon arrival even though we were a little late and couldn't contact him. Would stay there if I'm ever again in Palermo!