We did a tour from Palermo that took us to Monreale. It was a lovely town with a cathedral with the most beautiful gold mosaic ceiling. In the afternoon we walked around the sights in Palermo. I’m afraid Catania is our least favourite port in the Med as we have found the town dirty and crowded with quite a threatening atmosphere - I would suggest doing a tour from there perhaps to see Mt Etna. Cagliari is a nice place and easy to wander around on your own. It is a steep climb to the top, but pleasant to then have a drink or lunch looking down out over the harbour.