Hi Jacey,
What a great time of the year to head to the Walt Disney World Resorts! September sees lower crowds than the other fall months because everyone is back in school.
My family loves the water parks but they are not always a priority. However, during the hot summer months, you may want a day to chill in the water. September should still see some hot days.
Here is a method to decide. Look at the pool at the resort you are staying at. If you want to hang there for the day, it might be enough for your family. Pools at the resorts are fun especially at the Yacht Club, the Beach Club, the Polynesian and Coronado Springs.
Also, do you think you want to visit DisneyQuest or go golfing? If so, it might be worth the upgrade to the Water Park Fun & More. Pricing and options for the different
tickets can answer many of these questions.
Finally, it might be nice to try something new at the Walt Disney World Resort.
Wishing you a magical vacation!
Beth