Fortunately, I've never been the subject of any pickup lines at a regional or otherwise. I don't think they're very original or flattering.
On the flattery note, it's a complete turn off when a guy is like 'you're beautiful/amazing' when he first meets you. In my opinion, of course.
BUT I do have to say I met my current boyfriend at this year's Regional.
So, it's not like you have to use lines.