Terrible RC indeed. It has always been surprising to me the lack of a true luxury hotel in Seoul for Marriott. The W was gorgeous but in the middle of nowhere before it left the system. The Westin has a great location but was getting too old the last time I stayed there... and that was 6 years ago. I even felt that way 14 years ago.
I gravitate for luxury but stayed at Aloft last time and was pleasantly surprised. Location can't be beat and the price so low that my wife and I both enjoyed despite massive apprehension at staying. Only thing I didn't like was the so called gym.
I would like to try the RYSE, Autograph Collection as I love the Hongdae area.
The Hyatt is also nice but location not ideal. Stayed there several times and had nice service.