Phrae is a pleasant relatively quiet place to spend a day or two in, especially around the old town. It's quite laid back and pretty well off the tourist trail (we didn't see another tourist for the whole 2 days we were there). The food night market is one of the better ones we've seen and the streets are decked out with pretty fairy lights at night. The park in the center of the old town is buzzing at night with all sorts of activities. We watched a school basketball match for a while.
There aren't any sights to speak of, a few temples and a large Teak house on the edge of town is worth having a look at. There aren't many restaurants with English menus so we were forced to order a meal in Thai. We were quite chuffed when we actually got what we ordered.