Busan? Really? A nice enough hotel, but nothing stood out as special to me.
Siem Reap and Zanzibar are the ones I'd return to. Great hotels, amazing suites and staff.
I also stayed in Buenos Aires at the same time as Mick Jagger. If it's good enough for Mick then who am I to argue...
Tokyo is great, but perhaps hasn't been updated as it should because some people go there because of the movie and want it to look the same.
Milan is also very good. Lovely breakfast IIRC.