My first opinion- DON'T AUDITION FOR GREASE!!! Horrible show, in my opinion. Just had to say it.
Second, Hairspray is probably not the best choice, especially for professional auditions. You NEVER want to do something on Broadway at the moment. And you probably wouldn't want to do Good Morning Baltimore either because it's usually not great to sing a song by the other gender. There are exceptions but... If you are auditioning for community or high school theatre, however this is all pretty much irrelevant. In com. theatre it doesn't really matter because the people auditioning are usually kind of "off the street" and not as familiar with theatre.
Hope this helps. (except for the first part

)
"This table, he is over one hundred years old. If I could, I would take an old gramophone needle and run it along the surface of the wood. To hear the music of the voices. All that was said." - Doug Wright, I Am My Own Wife