Hi Zach - I just posted a reply to someone else's question referring to travel options around that time of year, so I'll cut and paste my answer again here, with a few modifications:
We had a fantastic trip 5 years ago starting in Rome, then took a cheap flight to Sicily, then back to the mainland to visit Sorrento and the Amalfi coast. This took us 3 weeks, so you'd probably want to only consider a portion of it. The trip was affordable, enjoyable, uncrowded, and not 96 degrees hot as it might have been in the middle of summer! Sicily has a few cities, but it's mostly countryside, with ancient Greek and Roman archaeological sites, fabulous mountain scenery, a few museums, incredible food, and again, in December it's not unbearably hot or crowded! We were on the move, driving a rental car in a counter-clockwise direction. We actually skipped the city of Palermo (the airport was many miles west of the city itself), but visited Erice, Agrigento, Syracusa, Modica, and lots more. The highways are toll-free and easy to navigate. Some country roads are narrower.
Rick doesn't include Sicily in his guidebook, but he did film a Sicily episode years ago, and inspired by that, and relying on a great Lonely Planet guidebook, we had a relaxed yet full experience, including a stay at the mountain agritourismo B&B featured in Rick's video.
We wrapped up our third week back on the mainland, driving up the boot to Sorrento and the Amalfi Coast and Naples/Pompeii. That was actually after Christmas, and people's fireworks displays on New Year's eve, shot off all across the sky was a great way to see in the New Year. Again, not crowded, not too hot, and all wonderful. For Sicily, if you want to see much, a rental car worked best for us.