Hello Melissa!
There is NO need to worry about your upcoming August Walt Disney World Vacation! The later you go in August the BETTER the crowds will be. In fact, you time you have chosen should be INCREDIBLE! You are going when schools are beginning AND before the start of Labor Day weekend.
While some would disagree with me, I always plan my visits to each Disney Theme Park around
Extra Magic Hours - which allow guests staying on property the ability to arrive early or stay late at a designated Disney Theme Park. There are some who say you should avoid the Disney Parks with Extra Magic Hours because there will be more people. However, this plan has ALWAYS worked for my family, ESPECIALLY when you take advantage of the morning Extra Magic Hours!
With that in mind, here are the scheduled dates for Extra Magic Hours in August of 2012:
Morning Extra Magic Hours (open one hour prior to regularly scheduled park opening)
Magic Kingdom - August 23
Epcot - August 24
Disney's Hollywood Studios - August 25
Animal Kingdom - August 20, 22
Evening Extra Magic Hours (typically extend three hours beyond a park's scheduled closing time)
Magic Kingdom - August 19, 24
Epcot - August 21
Disney's Hollywood Studios - August 20
If you have other questions, please let me know! I am here to help to any way!
Have a MAGICAL day!
Wes