Songs that help vocal power.?

i was wondering if any one knew any musical theatre songs that helped with voice power. This summer i want to work on getting a stronger vocal sound to prepare me for auditions through out the school year. I would like the songs to be uptempo since i am a teen and like to have fun when i sing and also i would like them to be for mezzo sopranos. And please avoid giving me a long list of song two or three is good enough. Thanks.