Fare Difference Delta v. Korean
 

I've booked a couple of U.S/China trips recently. Both times, I compared the prices on both the Delta and Korean Air websites. Last time, Delta was significantly ($600+ for economy) cheaper for exactly the same flights; this time, Korean is cheaper by roughly the same amount. Any idea why? Any downsides to booking through the Korean site? One upside is that I can choose my seats -- and pay a bit extra for the extra-legroom seats. A huge pet peeve of mine is that when I book Korean metal through Delta, Korean puts me in the back of the bus, middle seat; there's no way to change seats, and you can only buy the extra legroom the day of travel (assuming it's available).

The biggest thing IMO is flexibility, for regular economy it’s about $120 for change fees and $200 on a TPAC flight from the US to ICN. It could be more or less depending on what you’re booking though. But if you book with DL then it’s free changes and cancellations.