I earned two free one-way coupons on Southwest Airlines. I tried to redeem them for a round-trip flight in March, but there were no coupon seats on the return flight. So I redeemed one coupon, and have one left over. That’s a clever strategy by Southwest, as I will now use the other coupon as part of a second round trip.
Unlike the older trunk carriers, Southwest prices solely on one-way tickets – there is no gain to buying a round trip. That means that I have an incentive to pay (either with cash or coupon) for two Southwest trips. When I use my mileage to obtain a “free” ticket on the other main carrier out of Austin (American Airlines), it always pays for me to use it for a round trip. Southwest’s pricing and coupon policy ties me more strongly to them. American’s policy does allow use of mileage for a one-way ticket; but given their pricing policy, it only pays if I am planning one-way travel.