You will find a lot of information about bars on
www.koratmap.comIf you are 20-40 y-o, you might want to try Bar Nana, Update, U-Bar, George and Dragon, Swindler's, Walrus or many others. For DJ, Bar Nana, Update and U-Bar.
If you are over 40, you can still go at all these places!!!!!!!
Just last night, there were probably more than 30 people, USA, Australia, Canada, Sweden, UK, Switzerland, etc.. at George and Dragon with at least 80% of them under 40.
I saw you other post about 1 day trips in Korat. Try chokchai farm, Phimai (with a stop at Ban Prasat), Khao Yai, Korat Zoo and drive carefully! Many people got motorcycle accidents around...
Enjoy your stay.