Really good audition songs?

So, I'm auditioning for "The Voice" and maybe "American Idol". I have a very wide range and can sing nearly any style. I just am at a loss for a good song to sing. Something difficult, but something sing-able. They prefer something thats not suuuper popular, but is still known. Any help would be super helpful, but if you're just here for negativity; you can get the hell off of my question. Thanks :)