If I call a guy "very attractive" then that actually means better than just good looking, and my girlfriends are the same way. I think when a girl uses that phrase it refers to a blend of things--the way you walk, the way you talk, the way you hold yourself, etc. it's like a whole package deal.
Honestly there are some guys who I'd call good looking that I might not say they're "very attractive" only because it means something a little more intense and deep rooted. like, on a pheromones level. at least for me!