Gandolfi (can I cll you Gan?):
I spent 20+ years working in and around Washington DC, almost 10 years with the US Information Agency TV unit (don't jeer, I needed the money) and the one thing I learned is that most politicians have NO SENSE OF HUMOR when it comes to their image. Beyond that, what was her personality like. Was she warm and approachable, cold and distant, unreadable? Did she laugh and have a good time during the photo session or was it like a bad funeral? If so, she may respond to a more 'lite hearted" approach to a print. On the other hand, if she was cold, distant or unreadable, I'd favor a more straight approach. Less chance for fallout on you and the school.
I have a hard time telling from the three portraits where she falls in the 'warm and fuzzy' scale (10 is a purring cat that feel like a stuffed animal but licks your face, 0 is Dick Cheney) To play it safe, try making a semi straight one of her, but make a neg from the digipix and just go crazy on it.
All the best,