Hi Edward,
The Walt Disney World Water Parks are so much fun! My family and I recently spent a day at
Disney's Typhoon Lagoon and had an absolute blast riding Gangplank Falls (the family raft ride), circling Castaway Creek (the lazy river ride), and hanging out in the Typhoon Lagoon Surf Pool (the amazing wave pool). Whether you go there or to
Disney's Blizzard Beach or both, you're sure to have a great time. It will also be a good time of year for you to hit the water parks, as it is hot in Florida in August!
If possible, I do think that Walt Disney World will be less crowded from August 22nd to August 29th rather than August 27th to September 3rd. This is because Labor Day is on September 2nd this year. Since most people in the United States have the day off from school or work for Labor Day, there will likely be a spike in attendance that weekend. So if possible, and if you want to go at the less crowded time, I would go August 22nd to August 29th.
Have a great time at the Walt Disney World Water Parks, Edward! Please do not hesitate to ask if you have any further questions.