I'm at WDW now and the crowd level is quite reasonable. We haven't waited more than about 15 minutes for anything. Of course, we tour from opening until about 1:00 and then again from about 5:00 to closing, and we avoid the thickest crowds. We also use Fastpass at every opportunity. By the time we leave at 1:00, we see big lines at everything we breezed through earlier!
In the evenings, we don't try to do the big crowd-drawing attractions. I definitely recommend the afternoon breaks. Every afternoon when we return refreshed we see all these hot, miserable, red-in-the-face people leaving the parks. We just stroll in and start having fun again. In the evenings, we do low-draw attractions, eat, shop, and watch the evening entertainment (parade/show/fireworks). We are having a ball!
Edit: The weather is hot, but not too humid, and we are managing it just fine by getting out of the parks in the hottest part of the day. The evenings are quite pleasant.