High school plays!!!

I have recently purchased a 5D and am going to be shooting some high school plays which have low light. I would prefer to shoot without a flash, but would like some lens recommendations?

I do not want to spooke the performers by walking close to the stage or by p!ssing off parents by using the flash or moving around too much.

I any recommendations?

Mike

5D
24-105 L f/4
85 f/1.8
580 II