Where is the best place to stay for a beauty trip to Seoul?

Hi, this is Nana. I'm planning my first trip to Seoul for beauty treatments, and I'm wondering which areas everyone likes? I hear Gangnam and Apgujeong are famous, but what are they really like?

I think staying in an area with a lot of facilities would make getting around easier, but honestly, I'm not sure which areas are recommended. As a foreigner, I'm concerned about safety, transportation, and accommodation costs.

If anyone has experience, I'd love to hear recommendations like, "This area was great!" or "This place has great services for foreigners." Also, how much should I budget? Are the busy areas really that expensive...? I'd appreciate it if someone I can easily ask would help.