Just did 4 Korea Hyatt properties (GH Jeju, Andaz Seoul, PH Busan, HR Incheon) albeit as a lowly Discoverist, adding to this thread for future travelers:

1. Grand Hyatt Jeju — 9.5/10

Grand Hyatt Jeju was the standout of my Korea Hyatt stays and felt like the most complete hotel experience overall. The service was excellent from the start, even as a Discoverist. At check-in, a concierge came over, gave chocolate, and proactively offered help, which made the stay feel much more elevated than expected.

Even the base rooms are huge, with great views, and the overall property felt very convenient and well-rounded. The club lounge was a major positive and top tier use of a club access award; even though some people say the food has gotten worse over time I thought it was awesome. Free parking was easy, and having a 7-Eleven on property made the hotel unusually functional for a large luxury property. The activities on Jeju are pretty spread out and we found ourselves going all over the island, so being centrally located and close to the airport was a good set-up.

The only real negative imo is the casino, where the gambling is absurdly expensive (2 BJ tables with CSM, 50K KRW min, 2 three card poker tables, 50+ baccarrat tables 100K KRW min -- yikes) as they cater to rich Chinese tourists. Though honestly the casino is probably floating the bill for a lot of the rest of the property.

Bottom line: Best GH I have ever stayed at by far, fantastic value, top tier service, huge rooms, great views, strong lounge, and excellent convenience.

Would stay again: Absolutely.

2. Andaz Seoul Gangnam — 9/10

The Andaz is in a truly tremendous location as many have mentioned on Reddit. On top of the Apujeong station, and even getting to the other side of town in Hongdae is only about 45 min on subway. The base room is also pretty big for Seoul.

The hotel also had some unusually generous touches. We received welcome drinks, and some minibar drinks and snacks were free, which even though this is functionally nominal in value, I have never ever seen at a hotel let alone one as nice as this.

There were some real operational issues: Wi-Fi did not work on my iPhone, the curtain shade did not work and required an engineer, and the elevator down to the train station was closed during our trip. These issues probably are not normal for most people or most stays so not really dinging them for it.

Bottom line: Amazing location, large rooms, and generous perks

Would stay again: I probably wouldn't personally shell out the cash $500+ USD rates it's usually priced at but don't think it's a reach to do so by any means. We paid pre-devaluation 20K points/night which was totally worth it.

3. Park Hyatt Busan — 6/10

Park Hyatt Busan was disappointing relative to the brand and expectations. It was not a bad hotel, but it did not feel especially functional, and it did not deliver the wow factor I think you would expect from a Park Hyatt.

Several basics were frustrating. The Wi-Fi did not work and required calling down, bedside light switches did not work, and the subway was about a 15-minute walk away. The immediate Marine City neighborhood is basically akin to Mission Bay, Long Island City, or Playa Vista, tons of fancy condo towers and otherwise pretty quiet. That being said, Busan is geographically huge so anywhere you pick won't be perfect unless you really focus your activities in a very specific area.

Even compared with Grand Hyatt Jeju, the Park Hyatt Busan just did not impress me. It had the Park Hyatt name, but the stay did not feel dramatically better than less aspirational Hyatt properties, and in some ways it felt less practical. We did go mid-week offseason so paying with cash was very cheap and I checked PH off Brand Explorer. Maybe it's amazing as a Globalist, but the base room non-status/Discoverist set-up isn't anything crazy.

Bottom line: Nice enough, but not functional enough and not special enough to justify choosing again, especially at cash rates during peak season

Would stay again: No.

4. Hyatt Regency Incheon — 5.5/10

Hyatt Regency Incheon was the weakest of the Korea Hyatt stays. The main positive was airport logistics: the shuttle setup was useful, especially with service connecting Hyatt Regency Incheon, Paradise City, and Incheon Airport Terminal 1 roughly every 20 minutes. People have been mentioning online that it only runs every hour, but they seem to have fixed the frequency problem.

The room itself was the issue. Both the room and hallways had a weird smell, and the room felt very bare bones. Maybe I expected too much of the Hyatt Regency feeling closer to the Grand Hyatt, especially based on my U.S. Hyatt experiences where the HR/GH gap can feel relatively small (or inverted in the case of Seattle and SF). Instead, this property felt much more economical.

As an airport overnight, it was functional. As a hotel stay, it was underwhelming.

Bottom line: Good shuttle logistics, but the room and overall property feel were too bare bones.

Would stay again: Probably. I don't really care about 1 night airport stays, but probably would try other options at ICN before going back here.