We just returned from a quick weekend trip and it was hot and crowded, but we did ok. The only really bad experience we had was at Animal Kingdom. I love that park, but it is hard to do in the summer! We lasted exactly one hour and we were out of there (we're AP holders) because I couldn't take the heat, and so many of the attractions there are outside. They really need to add some of those mist machines along the walking trails! I live in FL, so I generally do ok in the heat, but I won't be going back to AK till at least October!! Other than that, we spent the days at Typhoon Lagoon, and the evenings in the parks and it was perfect!