Another vote for the Westin Chosun, stayed there in May and it was fantastic.

Free in room Nespresso machine and complimentary IPHONE 4 in the room for your use ( incoming calls free, 3G+ outgoing chargeable) can use for surfing at WIFI hotspots.

Place is just beside City Hall / center of Seoul, namdaemun, Myeongdong for shopping. Taking a cab from Chosun to Myeondong, the cab meter didn't even jump from the base fare of 2.4k won.

3min walk to the flagship LOTTE department store + LOTTE Duty free.

KAL Limo bus from airport drops / picks up at lobby of the hotel. ( 15 or 16k won? )

Near to the subway as well, just that koreans are very healthy, lots of steps in the subway for you to climb