Also, if you don't plan on using all the days, and plan on coming back, do some math and see if the no expiration option may work for you.
Last yr we bought a 7 day ticket, and had 2 days left and all our waterpark days. We upgraded what we had left and for slightly over $ 200 added a few more park days and the no expiration. We have a five day parkhopper left and 10 days of the wpandmore. So although we will use all the parkhopper days on our next trip, we will have a ton of water park days left that we can use forever or until they run out...lol. But I won't need to add the water park option on to new tickets for a few trips at least.
But definitely do the math. For us it worked out, but depending on the circumstances it may not be worth it.