Apart from Apache Bar, these three are where all the action is. You can hear them from miles away, so just follow your ears.
They seem content to ply you with free drinks, so take advantage of this offer. Have an hour off between 11 and 12, then you should be set for the rest of your night with your midnight bucket.
Jordan's is a faux Irish bar, with a live band every night and some sort of Guiness, they could almost be authentic.
Right next door is Tiger Bar, which powers out hip-hop and R & B mainly. The very friendly staff here ask you how much alcohol you'd like in your drink, or just let you pour it yourself. Check out all the messages on the roof as well.
Just up the steps is Reggae Bar, the one with the Thai Boxing ring (see DIY Thai Boxing entry). It's done up in red, yellow, and green, but that's where the reggae connection seems to end. It plays loud club tunes into the very small hours. Although it was taken over by hoards of moths a couple of times, forcing people back downstairs, the big deck is great for sitting and cooling off from your exertions on the dancefloor.
All three bars have people flyering every night. If you fancy a few hours of (hardly) work, in return for lots of free drinks and possibly free accomodations, then ask at the bar, or one of the tourists, busily handing out flyers.
Many nights of fun to be had between these three venues.