ASPD had a few threads about hotel bars and/or restaurants that were good for meeting women (pros or amateurs), but I don't see one on here.
So, let's start one. I cannot comment personally on more than one or two, as I have not been to many in the last year or so.
Ocean Prime seems like a hot pick-up spot, although I have not tried. Both times when I was there recently, it was a mid-week night and I was there with co-workers. However, I do know a UTR provider that hangs out there with her lady friends, at least one of whom has posed in Playboy (not a centerfold - lingerie issue). It seems like every time her group goes there, some guy in the bar gets lucky.
The only high-end hotel bars I have been in recently were ZaZa and Ritz-Carlton. Unfortunately, I was there with a visiting out-of-town friend, so I had no chance to flirt - although in truth, it seemed like every woman in both places was with someone. This was on a weekend night.
If you name a hotel or restaurant, please state the best night to go (if you know it).