It's been a year or two since I was in Bangkok, and I seldom stray too far from unchic Silom Road for nightlife, and things on the Web can be out of date, opinionated (as in the case of the second article cited below), or just wrong.
However, being curious, I did a search on Lang Suan and found at least three bars listed:
Paradiso Kara Club (see
http://tinyurl.com/2bdzrl)
and
The Tunnel (see
http://tinyurl.com/2egmu8)
and, of course,
I-Chub (see
http://tinyurl.com/2esz2s).