I think it ultimately depends on what you as a performer are comfortable with, but I know that Idina auditioned with "Something to Talk About" by Bonnie Raitt.
If my memory serves me well, she may or may not have sung "When a Man Loves a Woman" for her callback... but don't quote me on that, I may have just made it up because I like the song. =)
"It's not for sissies, contrary to popular belief." - Tommy Tune, on musical theatre.
My avatar: Yummy, no?