I have spent a few good nights at BATS (acronymn for Bar At The Shangrila). Thursdays to some extent, and Fridays and Saturdays are good as there are lots of regular folks there, both expat and Indonesian, but during the week it is pretty much a full on ayam bar with 90% + professionals and a bunch of sketchy bule business travelers. I suppose it depends on what you are looking for.

BATS also has pretty good food, but depending on who you are eating with you may want to clear out before 8 or 8:30 when the doors to the chicken coop fly open.

As these things go though, it is, IMO, the classiest of these types of bars and is a step up from Tiga-Puluh (le Meridien) and CJ's (Muliah Senayan) which are in the same category.

TJ