In planning a complex trip to Chile for 4 of us, there are some cases where one or more of us needs to take a one way flight. At present, one-way fares are often well above round-trip fares-for example,to fly from SCL to BAA (Coyhiaque, on the Carretera Austral) is as low as 150, but the lowest one-way fare is $221. It's also only 7500 Avios points plus $10, and multiple flights using Avios are available for most days in January and February (high summer there). I know--you could always buy a round-trip and throw away the return, but 7500 miles is even decent for something that costs
$120-150.