Where are the good service places located in Seoul?

Hello, friends! I'm Uyanga, writing to you from Mongolia. I'm planning a rejuvenation trip to Seoul at the end of this year, and it's related to good services. I've heard a lot about places like Gangnam and Apgujeong, but I don't really know how close these places are to each other or what the options for alternatives are.

Has anyone among you traveled to these areas? Are there any indispensable service centers there? And for foreigners, are there well-known and easily understandable locations? The plan is likely to be very short (3-4 days), so I want to stay in one place. I'm undecided, so I'm wondering which place to choose.

Furthermore, I'd like to know about the alternative options – are there clinics to contract with, recovery rooms, and finally, is there a good place to stay after receiving any services? Please share your experiences! 😊