If you have the opportunity to visit during a week day, I would strongly advise it. Weekends could get hectic, not to mention the heat and the humidity. Week days are usually slower, so you could probably visit a lot of rides with little to no wait during the first two hours of opening. Also if you are staying on the property, try to take advantage of the EMH. The last time I visited the Magic Kingdom during the summer was in '10, it was on a Tuesday in the middle of June. It was hot, but the crowds were somewhat moderate. Have fun on your trip!