User: How do I travel from SF to Aspen ski resorts?
Assistant: During winter season, United airline operates direct flight from SFO to ASE a few times a week. ASE is the local airport of Aspen. Once you arrive at ASE, most hotels and resorts offer complimentary shuttle to and from the local airport. Direct flight usually ends around the first week of April, so if that's not an option, you can either take a 1-stop flight from SFO to ASE, or fly into Denver then drive to Aspen. The drive is about 4.5 hours if the road condition is okay. If cost is a concern, flying to Denver and use rental car is usually cheaper.