The Coex and the Grand IC Seoul are located a stone's throw away from each other, and both are quite nice indeed. Technically, the Grand is the higher-end property but I'm not certain that I agree. Rooms at the Grand are a bit larger, I think, but the Coex's are still very spacious and a bit more up-to-date. No complimentary upgrades at the Coex, though, as there are only standard rooms (very nice) and suites.

The gym at the Grand is fairly nice, but the gym at the Coex is one of the best I've ever seen in a hotel.

Breakfast at the Coex is outstanding, and I'd rate it higher than the Grand.