I took DD12 to see Britney (and Jordin Sparks) last Saturday night and have to disagree with these posts. The worst thing she saw was Britney on a pole which was no big deal because at 12 she had no frame of reference for pole-dancing
The concert is circus-themed and had three rings with lots of "circus-type" entertainment including acrobats and clowns, that sort of thing. As for lyrics, I bought the circus CD a few weeks ago to listen to myself and then we listened to it together so we'd know all the words, lol. Can't think of anything on that CD inappropriate for a child.
The crowd at the concert was better than I had imagined and better than any county fair that I've been to

Why not go and if you feel that it is inappropriate leave? I think you'll find out that your family will enjoy themselves. Nothing ventured, nothing gained, and certainly nothing that is going to leave lasting damage