Hi Mindy!
Thank you for visiting the Moms Panel!
I think
Typhoon Lagoon would be your best choice, with plenty to entertain all the children in your party.
The older children will love the huge surf pool, the variety of the water slides and Castaway Creek, the 2100 foot circular river where they can float along through a rainforest, and caves and grottos.
For your five-year-old there is also plenty of enjoyment to be had at this water park. Ketchakiddee Creek has everything for little ones to enjoy - slides, fountains, waterfalls, mini-rapids and much more, all in a safe environment.
Full details of all the attractions at Typhoon Lagoon can be found
here.
If you have any other questions, please come back and ask me - I would be happy to help you plan your magical vacation!