Well, the "front row seat" would be the Italy - Germany bridge, but that place always gets crowded and is a pain to leave the park from. But other great spots are the Festa bridge, the docks for the Rhine River Cruise, Griffon's splash zone, Da Vinci's Garden, and near Roman Rapids. Those are the spots that I have experience with, but I'm sure my colleagues here on the site might have other suggestions/opinions.
I was pleasantly surprised by the view from Ireland. Some of the lower fireworks were partially obscured by the trees, but the view was generally excellent, and the music was loud and clear. It became one of my favorite viewing spots along with the ones mentioned already.