While many people here don't find it particularly appealing, I would take a look at Catania for a few days. There's enough there to fill a couple of days, and we found the food to be particularly good. You could do an excursion to Etna from there, too. Or Taormina might be another option. You could day trip to Etna from there as well. In addition, you could go to see the Riace Bronzes at the Archeological Museum of Reggio Calabria. It's a bit of a schlep, as you'd take the bus or train to Messina and then a short ferry ride. The train used to go from Taormina to Reggio Calabria because they loaded the train onto the ferry, but that was a while ago and I'm not sure they do that anymore. It would be a long day trip, but you could always stay overnight in Calabria. We did not have good luck with the train from Siracusa around Etna and to Randazzo, as the only one that would have allowed us to take that itinerary was cancelled.