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Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
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Posts: 100,399
There's very frequent airport bus service to/from the Westin Chosun, which is also extremely well located. IIRC there are a bunch of new Starwoods in Seoul, including one (aloft?) right at the train station.
OP says one night, but doesn't give details regarding whether there are business meetings (in Seoul), for example, the next day, or just another flight. If one isn't going to be able to spend time enjoying Seoul or has obligations the next morning (after a long flight the day of arrival), I'd pick the Grand Hyatt at ICN, but I've been to Seoul about a half dozen times so that it wouldn't be my one and only time to see the place.
Seoul can have bad traffic jams. It makes sense to pick a hotel that's well located for one's obligations the next day.
If the new maglev train is really operating to Incheon Village, that makes a lot of additional "airport" hotels into sensible choices, with some low key options for seeing a bit of Korea without going downtown. Otherwise, almost all of the "airport hotels" other than the Hyatt are a long ride from the airport. [It was so bad that it could be faster to go downtown.]