Sudak keeps rocking until late September. It has some fantastic parties and really loose morals in midsummer, I am told (including pre-parties at clubs starting at 6 or 8 pm), but it was still pretty good in late Sep. It is big enough for relative anonymity, but you will still bump into people you know on a regular basis. This is more of a mainstream holiday resort than Koktebel', so you won't have to cater to any New Age mumbo-jumbo to get laid. The only clubs open when I went were Dostluk (excellent food too) and the place opposite with more modern music (forgot the name). I can recommend Hotel Forum. Of the three places I visited, I found this the best for hunting sluts (or rather, normal girls acting slutty for the duration - 3 girls in 7 days); again, no *****s to be seen.
One point, if you ever go to the cinema (films in Russian) and the toilet is closed, DON'T go to the nearby park to relieve yourself during the movie, because the militsionery know the problem as well as you do. They will wait for you to finish your thing, then approach you with their flashlights and tell you what article of what law or regulation you have violated, and tell you of the dire consequences until you ask if the shtraf can be paid "on the spot" (i.e. a bribe). Cost me $10, probably overpaid by local standards.
Again, speak Russian. English gets you nowhere here. No English menus, hardly any English speakers.
Overall, with the possible exception of Sudak (especially during high season), Moscow is still a better bet for finding one-night stands, but then it will be easier here to score with a *pretty* girl for free than in Moscow. Usually, it ends in sex here at date 1 or 2, whereas in Moscow if a girl doesn't sleep with you the night you meet her she is often trying to develop a meaningful long-term relationship, meaning you may get to 3-4 dates, still with no result.