I have been worrying about ticket options all week. The pricing of the MYW tickets is really tricky!
Be warned if you have never been to the water parks before, the kids love them! I aksed my kids what they wanted to do on their next Disney vacation and the Water Parks was their #1 choice. A single day in the water parks might not be enough.
I finally ended up buying the 10 day, magic plus, park hopping ticket that expire after 14 days. There is little diffference in price between 4 days and 10 days. We will be going to the water parks and Disney Quest, so the Magic Plus option was a given. I debated a bit about park hopping. I ended up getting it because it has been handy in the past and it is not a very expensive option.
I elected to go with the expiring tickets. It is my understanding that I can upgrade to non-expiring anytime before my 14 days are up and pay the difference. Although the non-expiring option sounds like a great deal, especially to us since we tend to take 1 week vacations and could easily get two vacations in on a 10 day ticket, I did not buy the non-expiring option up front. There are several reaons for this. First, it is a very expensive option, although it has the potential to save us nearly $500 on our next vacation. I also don't want to feel like I have to ration parak days on this vacation. If we feel like going to the park for an hour on the day we leave, I don't want to feel that we are burning an entire day from our next vacation. If we spend all day in a water park, I don't want to feel like I am burning a day from our next vacation if we want to try evening extra magic hours.
When the vacation is over, I will then decide if I want to make the tickets non-expiring (assuming I understand the rules correctly). If they are less than half used, I will probably make them non-expiring, if not, I will just let them expire.