Whenever we go, I try to stay in one of the park hotels. It may cost a little more, but they offer busing to and from all the parks and Downtown Disney. That saves on the parking cost. also, they drop off and pickup right at the front gate - no walking or taking a shuttle to your car. A lot of the resort hotels also offer character breakfast/dinners. If the little one is into the characters, you could try this. It beats standing in line to meet the characters. If there is one ride you have your heart set on, get a Fastpass for it. It will give you a time you can return and get on the ride, usually in less than 15 minutes. Disney is pretty good about allowing you to bring snacks in. We usually carry a backpack with snacks, just check ahead of time what you can bring. Try to mix indoor activities with the outside ones, to give yourself time to cool down. There's a lot more, but you can find all that on the websites previously mentioned. Just have fun.
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There's never enough time to do all the nothing you want.