Go with whatever you feel comfortable wearing. You'll be and feel more confident. BTW, just because she is graduating in management doesn't mean that she wants a guy in a suit. Sometimes, it's the opposite. So don't try any doublethink. Personally, I would wear dark jeans, distressed leather shoes or boots and a well fitting long sleeve top in a subtle but not boring color (saw a perfect one - a sort of button up funnel neck by Armani Black Label a while back at Maxfield). And a casual jacket (a duffle, maybe) over that. A good belt is key. The look is clean, and says that you are there to get to know her, not try to impress her with your great clothes, while at the same time making it obvious that you are presentable and not a complete schlub.