I would like to say something about my case that might support lesage13's suggestion:
I emailed USC asking if there is any movement in the waitlist - yes, just that, didn't ask where I am on the list. And USC replied with an invitation to visit their campus, fully funded.
My sense is that they (maybe the nice ones) will invite you and fund your visit if they want to, without your asking.
To Philstudent: I will visit USC and syracuse too.
To add: if anyone is curious, they replied that there is no movement in waitlist so far.