I've got an upcoming long connection in ICN on Asiana flying BKK-LAX. Get in a bit before 07:00, depart about 16:30. I want to take one of those transit tours that do the highlights of Seoul city, maybe a 4-ish hour tour. I notice there are different itinerary offerings. Assuming that there is a choice of tour on the day I happen to be there, and the time frames work with my schedule, any recommendations, comments, or reviews from anybody who's done one of these? Failing that, any "top priorities" or "must-sees" that might help me choose tour X vs tour Y? I'm of a historical/architectural/cultural inclination.

I'll save the DMZ for a future visit when there's more time than just a connection to spend in Korea. And since I have lounge access, I can easily spend leftover filler time before the onward flight to LAX, so don't want to push and take too long of a tour.