Southwest has round-trip flights from Austin (AUS) to Denver (DEN) for $98, NONSTOP. $49 each-way. Flights August to October. No Weekends. Origin/Destination reversible.
Southwest allows for free carry-on, two free checked-bags, free change/cancellation and free in-flight refreshments.
Frontier also has round-trip flights for $55-$69, NONSTOP. $28-$35 each-way. Flights August to March. A few weekends available. Origin/Destination reversible.
Frontier allows for nothing. They charge a fee to change or cancel the ticket, they charge a fee for seats, a fee for any bag bigger than a small backpack and their seat pitch is 28-inches. No free refreshments. Water isn’t free.
We believe that the Southwest fare will be a better deal if you are planning on packing a real carry-on or checked bag, but Frontier has a few weekends available, and Southwest doesn’t.
Read More Nonstop Flights: Austin to/from Denver $55-$98 r/t – Frontier / Southwest