We had good luck in Frontier Land. There's a path from the parade route that leads over a bridge and straight to Big Thunder. We watched Spectro next to the entrance of that path, near the little refreshment stand. Not front row, of course, but it wasn't a mob scene and someone kindly moved over to let our daughter sit up front. We then watched fireworks from the bridge, where we had a good view of the castle. Not sure if that will be a good spot for Wishes or not, but it worked for Fantasy in the Sky.
This was in April, a few days before Easter, so the park was pretty crowded, and it was still a good spot.