I haven't had the chance to play much in Seoul. I've heard Haesley Nine Bridges outside Seoul is better than their course on Jeju, so it would be worth checking out if you have the connections.
South Cape club is in Namhae which is a 4 hour drive from Seoul. I haven't checked it out yet but will try to have a look on my next trip there in June.
About an hours drive west of Namhae, DMK have just built 27 holes on Gyeong-do, a small island off Yeosu. The amount of earthworks involved here was incredible. The following link will give you an idea of how much of the island the course occupies. The course is in play now.
http://www.yeosucc.co.kr/Try to get organised with bookings as early as you can, making single bookings or getting a game without a booking can at times present problems in Korea.
Great people, enjoy a few soju's after your round !!
Cheers
Greg