Probably won't be as crowded (I've heard the last two weeks of August usually aren't) except for Thursday-Sunday of Labor Day weekend.
It will be *extremely* hot and humid...I can guarantee it.
That said, we spent Labor Day weekend at WDW 6 years ago...and it was still bearable. Took advantage of EMH...and then headed to the pools in the afternoon.
Nice to have the space and serenity of the GV to go back to after a day in the hot parks