I just booked a trip from SFO to ICN for October. When researching fares, I noticed something quite puzzling. If I purchased one way tickets in each direction, the price was about $500 less than the very same itinerary booked as a roundtrip. The dates, flights, and fare codes (R) were identical. Needless to say, I purchased the one way tickets in each direction. A friend of mine recently encountered a similar phenomenon when researching a booking to Taiwan, so apparently it wasn't an isolated occurrence. Does anyone know why this is? I was certainly happy to save a bunch of money when booking my trip, but remain puzzled by the pricing methodology.