Hello all.
I've seen the other threads with 5/10/12 hours in Seoul, but I hope to get more ideas for our stopover as it is slightly longer.
So, the two of us (me and wife) will be landing at ICN on 15th of January at 17.55 and departing on 16th at 13.10. We should not have to take our luggage, hopefully.
As we have never been to Seoul before and from my initial research it looks like a great city, what would you recommend to do during this time?

I'm guessing we should be able to get to the city by Express train around 19.30, so could do a little Seoul by night until around 12.00 - 01.00 (what's your best choice for this?).

Can we still use the City Airport Terminal if we already have the boarding passes (do immigration checks there) so we can head straight to the gate?

Is it worthwile taking a hotel in the city or we should get one next to the airport and just head back there after midnight?

Thanks for your help.

I would say to go straight into the city. Check in to a hotel perhaps near the center of the city (see Luxury Hotel thread for hotel ideas such as Westin Chosun, Plaza, Lotte etc.). Then you have a bit of time to explore the city. Maybe you can get a good Korean dinner before retiring for the evening? Korea House Royal Cuisine might be one option. If you have time after dinner, why not check out Myeong-Dong Night Market area. Youtube video of Myeong-Dong. Or Cheonggyecheon Stream. Cheonggyecheon Stream is a nice place to visit.

Hotels near the airport are good but boring. You can get a better feel for Seoul just coming into the city. If you take the Airport Express train, the Seoul stop is many levels below ground. It might feel like you have to take multiple escalators and/or elevators to finally get to the ground level. The entrance/exit to the Airport Express is near the Rear entrance to Seoul Station. Taking a taxi from there to your hotel might be a good option. The other option is to take the escalator up to the main floor of Seoul station, walk all the way across and then head down from the main entrance of Seoul station where there is usually a line of taxis outside. Or if you feel really adventurous then jump onto the subway and make your way to your hotel!

January tends to get a bit cold so be prepared.

Also regarding the City Airport Terminal, it seems they only handle check in and immigration if you are flying Asiana, Korean and Jeju Air.

Have fun, let us know how things turned out for you.

Thanks nme7. Will surely get back here with my impressions.

I'm flying Korean Air so I should be able to go through immigration at the City terminal.

Cold - will be prepared. I'm coming from Australia so it will be quite a shock, but I'm headed back home to Bucharest where so I have to get used to it