Re: How would you classify it?
My definitions for the terms you're asking about-
Classic- has been around for centuries, ie John, Michael, Elizabeth, Mary
Modern Classic- hasn't been around as long as classic, but has some sort of roots; It could have started as a literary name, ie Angelica, Jessica
Dated- was extremely popular for a while, but dropped because of how popular it became, and became less popular because of the popularity- ie Jennifer, Deborah
I don't think I'd call Vanessa dated, especially since I've met only one Vanessa.