Whether it's a good idea to route along the side of a hill has a lot to do with the slope of that hill.
If the slope is more than about 8%, then you are going to have to do a lot of grading to stop balls from bouncing and rolling to the low side of the hole in the landing areas of the par-4's, and the more steep it is the more awkward it will look. Spring City, mentioned by Michael, is extremely steep, so that's what had to be done ... it looks okay because the clubhouse is at the top and you are always looking down toward the lake. From out on the lake it probably looks AWFUL.