Katy Perry - suitable for 7 year old? Album recommendations please

[PuddleUK]

Ok so the subject shows just how out of touch I am! My just turned 7 year old has until now been happy to listen to the likes of Scissor Sisters, Blondie, Beatles, you name it but I'm not exactly up on the charts. (I should add we're living in a non-anglophone country) She's now picking up bits and pieces from an American girl in her class and I'm happy to broaden her musical outlook provided it's age-appropriate. So what do you advise? Katy Perry? Taylor Swift? Any others? Ideally something that won't drive me too nuts on long car journeys when it's her turn to choose....