Amy-
I fell in love with Girona when I visited in the fall of 2002. In fact, I arrived with my friends and was only supposed to stay one night but ending up telling my friends to go ahead without me and stayed another.
The old, hilly quarter has one of the best preserved juderias in all of Spain. You could wander this area for hours. There's a very helpful tourismo by the river that will arm you with a good map and plenty of ideas for the day. If you want to try some pinchos (basque tapas but presented like works of art
) there's a great tapas bar in the old town. I'll post the name later when I can find it!