Welcome to Seoul! From an American/European perspective, the city is very much like Tokyo or Hong Kong. It has its subtle differences in people, places, and habits though. Enough with the intro, on to the guide.
Your phone should work in Korea. You can get a 4G hotspot or SIM card at the airport without much of a hassle. Getting one in the city is a hassle. There’s a good amount of free wifi, but it’s not everywhere.
Busses and subway stations are all over the city. The transportation is generally quick and efficient, if not especially comfortable. Subway is your best bet, busses are mostly in Korean so not for the feint of heart. Look out for the little old ladies elbowing you out of the way to get a seat. A “T-Card” can be used on busses, subway, and taxis all across Korea!
Gang nam is the main business district. There’s tons of city things to do there. The 64 building is a popular place to go and look at the scenery from the top. The famous song about their style is apparently a parody.
Namsan is a mountain with a nice little hike and there’s a big tower at the top that’s good for views of the area. It’s near Itaewon which is the main foreigner area. It’s a nice place to walk around and can make for a nice day.
Hongdae is a college area with lots of bars and drunkenness. But they also have lots of live music – people playing music out on the street in parks on the weekends as well as in some of the bars. It’s a neat place to spend an evening strolling around.
The typical tourist sites all looked the same to me. The main palace was kind of neat to see but then others are just repeats.
Locals know of the best food, drinks, coffee shops, etc. Doesn’t matter where they take you, the favorites are all really good and the only difference for American palate is preference and location. Definitely hit up a Korean BBQ place. Very different from the US version (don’t bring your nice clothes, it gets smoky). And have some of the cold noodle soup dishes. Karaoke (pro-tip: it’s called Noraebang) is ubiquitous in time and location.
Koreans are friendly and helpful as a rule, but they might be considered socially awkward. Being less than perfect makes them feel embarrassed and ashamed. Every Korean seems embarrassed about their skill with English. So asking a question or interacting is likely to elicit a nervous giggle, and they may not answer you for fear of seeming not to be fluent. At least until they have a drink or two.
Koreans drink more on average per year than even Germans. Beer (makchu) is expensive and the local stuff is foul. But you’ll have a lot. Soju (distilled liquor) is a bit sweet and is used as Russians use vodka, but its half that strength. Makoli is a kind of traditional peasant’s drink that’s milky. There are some places that serve it traditionally in a bowl with a ladle you will share with the table. Definitely worth trying but know in advance that you’ll have a little diarrhea in the morning from the amount of yeasts in it (its a normal body reaction, not montezuma’s revenge). Bekseju is not to everyone’s taste but I like it. It’s called a 100 year wine because supposedly drinking it will help you live 100 years. Koreans change drinks often and there’s no such thing as the “beer before liquor” rule. Beware the So-Mak – a mix of Soju and beer. It’ll sneak up on you. Be prepared to drink with Koreans until 5-6am, get an hour of sleep, and go to work.
Korea is the most wired and technology loving place I’ve ever been to. Mobile phones are in everyone’s hands at all times. And everything has weird little jingles it plays. Even the toilet has like 50 features and plays a song. You’ll get used to it quickly.