Get down on some Korean food - you should be able to pack away a Korean-size meal at 2-3 hour intervals if you keep walking and sightseeing. For one ideal very big sightseeing day, starting in the morning, run a slalom course with a few hops between, and you should get the important stuff down: Take the subway up to Jonggak station, exit 3, walk straight down the Jongro (main street name) and hang a left when you get to the first 4-way intersection; there's a Burger King on one corner, a Giordano on the other, a park across the street, and you turn away from all them and take a left at that corner, and then a left onto Insadong-gil. Roll down Insadong, lots of souvenir-y stuff, things to see. From that far end, walk all the way to the other end, there's a convenience store to your left on the other end. From Insadong - take a soft left and walk down the main street, and you'll come to a big Korean palace looking thing a couple blocks down, Gyeongbukkung - you can go in and check out the old palace grounds and there's a national museum in there as well. From Gyeongbukkung' go back out the main gate there on the 'T' intersection and walk straight out, down the street. You'll pass the US embassy, a new little plaza thing they've built in the middle of the street, and then once you get to Kwanghwamun station, you can go into the Kyobo bookstore there if you like, it's underground and you can access it from the subway underpass. Lots of stuff in there. From Kwanghwamun, keep walking away from the palace down the street, and you'll pass the entrance to Cheonggyecheon, it's a stream that passed through Seoul that they've restored recently and there's always something they're doing down there. From there; you can down to city hall and find the Seoul Museum of Art, Chagall is on for the next couple months, you can swing past City Hall and see what they're doing on the front lawn (maybe ice skating) and then take a left down to the Lotte hotel/Lotte department store. I wouldn't spend tons of time in Lotte but it's worth a look. Lotte Department store is opposite Myeongdong, which you will want to check out. Myeongdong main streets are shaped like an 'L' so go away from Lotte, and then take a right up to go up the other main drag, you'll be able to tell because it will have tons of people, as opposed to lots of people. There's a lot of chintzy-type stores and stuff to check out in Myeongdong, it's a mainstay old shopping street. From Myeongdong - you can check out Namdaemun market, which is pretty close. Once you're done with Myeongdong - take the subway or a cab down to Apgujung, walk around 'Rodeo Street' and check out the high-end boutiques around that area - there's a whole strip of designer flagships in Cheongdam-dong away from the Galleria, plus 10 Corso Como in that area as well. That would probably be a whole day of sightseeing alone, but if you're up for more: In the early evening, head up to Dongdaemun, check out Doota and Migliore to see the most clothes crammed into one space, that goes on all night. Nightlife: a one and only night should include some sort of drinking, at least mildly. There are plenty of bars, fortunately, and tons of clubs but they aren't going off unless it's Friday or Saturday.