A fifteen-foot white hose will work most of the time. To top up your freshwater tank, It is a good idea to have two of those if your fresh tank inlet is not on the same side as the hookups.
I carry 200 feet of ordinary garden hose (four 50-foot lengths) for those campgrounds that do not have water at every site but do have a water tap for common use. So far, I have been able to camp within 200 feet of the tap. (That seems to happen to me about every other year.) Not everyone would want to bother with this or have the space for it, but I have enough space in the center of my fifth-wheel's pass-through storage.