I stayed at CSR this pass june. It was beautiful, and the themeing is great! There are 4 bus stops located around the resort b/c it is pretty big. We stayed in the cabanas, building B (i think it was B?) and were pretty close to the main bus stop, beach (just a some sand and hammacks, but still pretty cool), pool, and main buliding. Some of the casitas are even closer to everything, but at night i liked looking across the lake from the cabanas and seeing the casitas... it looked like a little mexican city on the water. When my family arrived we had no idea in which building to stay either, and so one of the cast members was really kind and helped us pick out a great room.
PS: i wouldn't recommend the ranchos, they looked really pretty, too, but they were the farthest away from everything. However, there are bell service people who sometimes pick people up and take them to the main building. We never were offered a ride, but supposedly people sometimes are.