Let me preface this by stating that I hate hot weather, especially humidity. We went last September and would go back in a heartbeat then. Yes, it was hot, but you literally walk right onto rides. Our first morning in MK, my DH said, "we've ridden more in 45 minutes than we did in an entire day last May." And that was the truth. In my opinion, waiting in line all day and only getting a handful of rides in is not worth it and is almost unbearable if you have little ones with you. If you can ride so many rides in the morning, you can afford to go back for an afternoon swim and return in the evening without feeling like you're "missing" something.