There are two main airports close to Seoul. Incheon International Airport and Gimpo International Airport. Gimpo Airport was South Korean main International airport in the past but due to the increased number of air traffic it has been replaced by Incheon Airport in 2001.
At the moment Incheon Airport servers mostly international flights and Gimpo airport serves domestic flights.
Airport tips:
You can check in for your flight and drop your luggage at the Seoul Station and CALT. More details here.
Interesting facts:
Incheon Airport is at the top of the best airports lists for years and currently holds the 3rd place in the Top 100 Airports list by Skytrax.
Entry cost:
$42 Day Pass through loungebuddy.com
Entry cost:
$36 - Pay for entry at the front desk
Concourse A (inside security)
Concourse A (inside security)
CHEAPEST:AREX All Stops Train
— KRW 4,150, 58 Minutes from Seoul Station
Fastest:AREX Express
— KRW 8000, 43 Minutes from Seoul Station
Best:
— both options are great, it only comes down to saving more money or more time
If you are not after the lowest price, then I would recommend using some Asian airline as almost all of them are regularly placing on the top of the best airlines lists.
Two major Korean airlines are operating non-stop flights from the big airports around the world. Korean Air (Sky Team) and Asiana Airlines (Star Alliance). They are both very well known, and the differences in quality and service are minimal. Usually, when I am booking tickets to Seoul, Asiana Airlines flights are a little bit cheaper.
The decision often comes down to which alliance mileage you are collecting.
Airline tips:
I prefer Asiana Airlines because of the Star Alliance.