If we get the 7-day park hopper w/ no expiration and water parks option, does that mean that the water parks days that you get are in addition to the 7 days? Or does it just mean that of the 7 days, we can use those days at the water park? If that is the case, why get the water park add-on to a non-expiration ticket, when they are a good bit less in price than the theme park tickets?