Can't help too much as I'm a mezzo, but maybe I can put you in the right direction. Try looking at Kristin Chenoweth songs. I wouldn't suggest doing anything too popular (Wicked, Glitter & Be Gay, etc) but it always helps me find audition songs to look at everything similar singers have done. If not Chenoweth, who are your favorite sopranos? Maybe check out the resume of one of Broadway's recent Glindas, Christine Daaes, or even a Cosette. Hope this helps you, and break a leg at auditions!