We always go to WDW in mid to late July (this year it's July 12-19). It will be hot. It will be crowded. But hey, you're on a Disney vacation!!
What we always do is try to get to the park early (at opening time if possible). We try to avoid the EE park. Plan ahead for what rides you want to do. (The Unofficial Guide is great for that). Use Fastpass for the popular rides. WE go for three to four hours then go back to our hotel to cool off, nap, swim, or whatever. Then we head back to one of the parks in the late afternoon. The crowds have usually thinned out.
It is likely that there will be afternoon rainstorms a few of the days you are there. That tends to reduce the crowds.
We've found that going back to our hotel is a key to enjoying the trip. Later in the afternoon it's common to see some people that have been going strong all day, and are beat from the heat and the crowds. They ARE NOT having fun at that point. Don't try to everything and enjoy the trip.
Greg