I personally think a well-executed acoustic guitar singalong can add a lot of real joy to any group experience.
I've played in rock bands since I was 15 (I'm north of 50 now), and I've been on stage in front of a thousand people and I've played to killer mosh pits and all that, but my best memories of all those years were the after-parties where it was just me and my bassist with acoustics and a room full of drunk people singing along to the Eagles or Sublime or maybe even Weezer...
Now, it helps to have a professional level acoustic guitar and, of course, a professional lead singer to hide everyone's mistakes, but it can be a magical, cathartic experience when the room all sings at the top of their lungs...
Great memories.