Whizzy,
Really depends on what the bar is looking for. Basically every bar or dance club have facebook or certain website, probably a twitter. I don't know about America, but they surely have something on board to advertise. I suggest paying attention to what the bar is doing, like events on a certain month, probably discount on a certain liquor or invitation, a guestlist provided by a certain company so as to invite more people to come and know the place. This companies usually helps clubs with advertising.
So yea, depends on what they need and offer to people. Some of this clubs and pubs do this
- Large television for World Cup this month. (You can suggest inviting people and give them discounts, Chase has this in one post, "playing the host" and another in an article)
- Modelling gig once every few months. (My acquaintances invite me every now and then. You can offer value by being the cool guy there or invite cool people, probably high spenders will be better)
- Dance clubs (like a Kpop night or retro night, So you might probably invite people of similar interest)
All in all, it is the customers, what value can your customers bring, and what the club has, and what they can offer. It's abit of here and there. Hope this helps a little. 
Zac
