We stayed at the JW Marriott Seoul for six nights for our first visit to Seoul. Overall, we thought this was a great hotel in the city.
Firstly, the standard room was very spacious, with a very large king bed, sofa, and desk. There was a column in the corner of the room by the desk, but we found this didn't bother us. The view was towards the mountains away from the Han River, which meant we could faintly hear cars outside. However, the noise was very faint and didn't keep us awake. The bathroom was spacious with a powerful shower. Unfortunately, the toilet had a slight leak but this did not bother us and we simply put a small towel towards the side to absorb the water. Lastly, the room was cleaned very well by housekeeping who also performed a turn-down service.
Secondly, we had breakfast at Flavours as part of our stay. It was a buffet-style and there was a large variety of food and drinks. The food and drink options remained the same each day, but it was tasty and we enjoyed it.
Thirdly, the hotel is very well located. We went exploring in Seoul every day and it was very easy to take the underground and buses, given the hotel is next to the "Express Bus Terminal" station. It was also well situated for the airport limousine bus (6020) which dropped us off outside. There were also lots of restaurants and shops nearby, which made topping up the T-Money card quite easy.
Lastly, and importantly, the staff were very friendly and helpful when we needed them (some sellotape for broken glasses)!.
All in all, we'd highly recommend this hotel if you wish to do a lot of sight-seeing in Seoul!