I do not like the Sims 3 Showtime stages, I think they are small and as everyone knows, real concert stages are not small.
This is what the stage would look like empty.
Adding the audience and the band, looks almost real.
With the screens, I cheated to get the effect of the TVs, I used photo scape.
There is a dressing room on each side of the stage.
There is steps to go under the stage. I didn't take the time to do under the stage, but you can.
Ok for the fun stuff, you will need the following:
Concert stuff here
Fly cases here
Concert speakers here I believe you have to be registered.
This should do it, if you have any problems let me know in the comments. Thank you.
I used OMSP as well to get the drummer to be on top of the platform. You can also find that here