Hi! I've seen people that say to stay away from Sondheim during an audition (although I'm not sure why as he's a genius) but I just think as long as you are confident in the song, you should sing it. From the list for the Witch (which is a role I'll be auditioning for soon as well), I would choose either "Another Hundred People," or "Some People." They're both at a faster pace, which is very Sondheim like, especially in Into The Woods. Break a leg! :)