First off, remember that these remarks are subjective and hardly definitive: Sicily is beautiful, confusing, and challenging for travelers of all ages. It has its own peculiar rhythm in which time seems to slow down. The coasts, for example, are remarkable, but rarely visited comprehensively because they’re a bit often the beaten track (with the exception of few famous resorts, Taormina, for example). Probably the best way to see it, honestly, is with a rental car and time on your hands — allowing for misadventures. But if you want a more realistic approach, I think your best bet is either spending some time in Palermo and Catania, and moving out from to nearby local towns, or taking a tour. If you do plan a tour, get is straight before you leave. You don’t want to find yourself in Sicily making it up as you go along, unless you’re extremely adventurous. As for time of year, avoid the high season. Shoot for October, even November. The climate is temperate. Sicily is always about 5 to 10 degrees warmer than Rome. Another option is March, before Easter, or May, just after. June through September are the hottest months.