Which beautiful districts in Seoul are you interested in visiting?

Hello! I'm Bayar, from Mongolia. I'm going to Seoul at the end of this month and I'm looking for a place to get female beauty treatments. I've heard a lot of good things about Gangnam, but how expensive are the prices there? I think Apgujeong is also the same.

Where do people actually stay? Is it better to stay near Gangnam, or is another district better? Since I'm a beginner, I usually move around for the last month. I'd like to get some advice from experienced parents!

Also, what are the pros and cons of meeting or not meeting people here? My friends say that foreigners get good treatment. If you've been there before, which beautiful districts would be more suitable?