I fly ORD-ICN regularly and two things come into play: First, on the way there, there's a deviation from the ideal great circle route (essentially along the south coast of Alaska) in order to give North Korea a wide berth. Second, on the way back they usually fly almost due east across the Pacific, following the jetstream. The way back is usually shorter by 60-90 minutes due to the tailwind.

So, yeah, I long for Reunification for the selfish reason of shaving an hour off the flight time to Seoul.