We used Mario Astone in Messina. Her gave us a wonderful day in Messina, Taormina and Castelmola. I understand from other postings that he also does a tour that takes you up to the craters at Mt. Etna.
I arranged a tour for the other part of my group with Etna Experience. They ddid a private tour just the 4 of them with with a licensed driver/guide who specialized in volcanos. They went to the volcano and also visited the gorge, and inside a lava cave. Also included was lunch and wine at the Gambino winery. I can vouch that the wine is really good since they brought us back a few bottles. They made it back to the ship on time and both groups had perfect days with the things they wanted to see.