I know a lot about the bar scene in Escazu, I go there every weekend.
Fandango is a nice place to go after midnight, or get there even later. Everyone goes over there after the bar they were in starts to give them last call.
Best palce to go either Friday or Saturday would be Privรยฉ, it's owner is a gringo and the place is always packed with classy middle aged ladies. Bunch of local models go party here.
http://privecr.com/
It usually closes at 4am, and you can head to Fandango if you feel like partying a little more.
Ladies Night is Friday at Privรยฉ, free drinks for the ladies, no show.
I also visit Friends for ladies night, it is on Tuesday. The same owner has the bar next door, Ebony56 which has ladies night on Thursday, bunch of horny girls (not the classy type) that will be very friendly in exchange for drinks. They love gringos by the way. Most of the girls go only the admision fee, they are not the wealthy type, easy place to hook up in my oppinion. You will even see a bunch of the HDR girls getting there for these ladies nights.