Hi Claire,
I am glad that you are planning to spend some time at
Disney's Typhoon Lagoon Water Park. My family loves splashing at this water park!
Which theme park you decide to split the day with and which you experience for a full day will depend largely on your family and their interests. If your children are excited by exotic animals and would find a day seeing the likes of tigers, gorillas, and elephants to be wonderful, I suggest that you spend a whole day at
Disney's Animal Kingdom. If Star Wars and thrill rides are more to the speed of your family, they will likely enjoy a whole day at
Disney's Hollywood Studios. Both of these theme parks have plenty to do for a whole day, but you can hit some highlights in half of a day.
Another variable to consider is timing. Disney's Typhoon Lagoon Water Park typically closes fairly early in the evening, around 5:00 or 6:00 p.m. My family and I find that the best time to ride the water slides and attractions at Disney's Typhoon Lagoon is early in the morning before other guests arrive and lines build. I suggest that you consider going to Disney's Typhoon Lagoon early in the day - arriving 15 minutes or so before the posted opening time - and then leaving mid-afternoon to head to a theme park. Disney's Hollywood Studios typically has hours that go later into the evening. This would help maximize your time. While Disney's Animal Kingdom currently typically closes earlier, this may soon change as Disney is adding nighttime experiences to this park. Operating times of all parks vary. I suggest that you check the hours for your specific dates to help make a decision.
Please do let us know if you have any further questions, Claire!