I had complete fears going in July last year. We have normally been during less crowded times. The only advantage we had for this trip is that we were there 6 months earlier. We have also been many times prior. For us, it is do the biggest things you want to do early and fast. As the herds get caught up in longer lines, the smaller rides have quicker lines. We made plans that we would spend the entire afternoon at the resort and decide what we wanted to do at night. Most of the time it was pin trading at DtD. I was actually surprised at how much we got done in the mornings until about 1PM. Then it was back to the resort for hours of pool games. My daughter said it was the most fun trip she had because she was able to just have fun and not rush around.
If you are staying in the parks past early afternoon, you are dealing with high heat, high humidity, massive crowds, parents getting near wits end, kids getting cranky.