Bob, We are taking this tour in the beginning of September, and I was going crazy trying to figure out the air travel for this trip. I was considering going from SEA to MXP (Milan), spending the night in Milan and then taking EasyJet from Milan to Palermo. Lufthansa has some great prices going from SEA to MXP, although it is not a direct flight. EasyJet has a number of flights that go from Milan to Palermo and from Catania to Milan. Ryanair also has flights from Catania to Milan. Please note that EasyJet does not yet have a schedule out for November, but you can look at their October schedule to get an idea. I also wanted to avoid Alitalia because I was not confident about the future of the airline (not to mention the possibility of strikes). I also looked at taking a flight that went from SEA to LGW or LHR which would be direct. The plan was also to spend the night in a hotel and then take one of those low-cost European airlines to Palermo - same plan for the flight back.
At least you are taking this flight from Seattle, We need to fly out from Spokane, which makes the air travel to Sicily even more torturous! My flights are booked, and they are very interesting to say the least!