@igazor @KatyJay88 Funny you should ask today. This morning I was just playing around with the Venues xml and Bars xml attempting to change the hours of various lot assignments. I haven't tested the two mods I created yet though. Dunno if I was successful or not.
Both xmls look like they control various lot assignments. So, as igazor said, changing the hours for the poolside club assignment will change the hours for all poolside clubs in every world. It's not possible (AFAIK) to change the hours of an individual lot. My impression from the dev comments in the xmls was that bartender hours should follow the lot assignment open and close settings, and that there are separate bartender hour settings (in the bartending xml) in case the lot assignment doesn't have open and closing times. But like I said, I haven't even launched my game since creating these 2 mods; I don't know if I'll run into the same issues that igazor describes. I think I have everything set to the same times though.
Shimrod's 23 hr bars and clubs mod works in my game (and alters the Bars and Bartending xmls). That might be a solution for KatyJay88. His mod is available on simsasylum.com. Free registration required for view and download. Shimrod's forum is in the retired creator's section. I basically followed what he did but set bars and clubs to be open 20 hrs. That mod doesn't alter the Venues xml. I created a 2nd mod for the Venues xml to alter open/close times for other lot assignments in that xml.
The Venues xml is what Shimrod's Townies Out On The Town mod alters. I was looking at his changes after a recent Chatterbox discussion about that mod. I decided not to use his changes to how many sims the game pushes to lot assignments, but I noticed that there were open/close times for some lot assignments that I wanted to change. Primarily the Seasons festivals. I'm hoping my changes work. I'd love for the festivals to be open just a bit earlier. Most of the bars and clubs though are in the Bars xml.
TL:DR - Yeah, just today I took a stab at working with the Bars and Venues xml to adjust open/closing times for various lot assignments. Haven't tested whether they work or not. I spent the rest of the day terrifying myself with a HOPA game. :p