I havent been to
Galway myself but i have many friends who have. It seems Galway is becoming more and more popular, especially for its nightlife. I know many groups having travelled to Galway for stag nights.
I know that if you are lookinf for a pub with live music you can go to Monroes and the Kings Head. I had a look at a website and found a list of over 70 bars and clubs so i really dont think you will have a problem finding somewhere.