| Cheap Flights: Austin to/from Denver or Chicago $98 r/t â Southwest Southwest has round-trip flights from Austin (AUS) to Denver or Chicago (DEN, MDW) for $98, NONSTOP. $49 each-way. Most flights are between January and April. Mostly on weekdays. Origin/Destination reversible. Note: You can save up to an additional $150 if you book your Flight+Hotel together as a package on Southwest Vacations and use the US150OFFÂ coupon-code at checkout. Before you commit, always compare the prices of the individual Flights and Hotel with other hotel booking sites like Expedia or Tripadvisor. Read More Cheap Flights: Austin to/from Denver or Chicago $98 r/t â Southwest . | 