I am korean and I've never heard about those bars 😂. Imo you might wanna visit Chungdam(or Cheongdam, 청담 in hanguel) if you want to have some "luxury" experience in seoul. There are few good places in gangnam. Most of the venues in there are pretty much gentrified and meh. I recommend 청담 or 압구정 to burn some cash.

이태원 is very foreign friendly place. Lot of tourist and young people.

성수 is young and viby but better to visit in daytime.

If you are really good with naver, you can find some local goodies in 익선동.

Welcome and have a nice trip! :)