I have access to a condo off Ploenchit.
I lived off Soi 8 several years ago.
Ploenchit to me is great out of the way from lower Suk which is like a slum in my opinion. Drunks, bums, hookers, and thieves at lower Suk 24/7. Soi 24 is OK, the Japanese, Koreans and Chinese seem to love it.