I enjoyed staying at Marisas Flat. It was very clean and the communication was kind and easy. You even have a small balkony overlooking pretty houses and the mountains.
Mondello beach is only an easy 12-15 min walk away. (I recommend going there early if you're travelling in august.)
Mondello beach is quite easy to reach from Palermo city center. It takes about 1h. Just take bus 101 and 806 (check google maps) from the railway station.
I'd stay here again! Grazie.