Raji,
I probably overstated not using your car when it comes to the Magic Kingdom. But when you go to any of the other parks you are parking in lots where getting to the park gates is either by direct tram, or even walking. In the case of the Magic Kingdom, however, you are parking much further away. First you tram or walk your way up to the Transportation and Ticket Center. But at that point you are still a boat ride or monorail ride away from the park. But if you use the Disney bus system, you are dropped off a quick walk from the park gates.
The difference in transportation time is about 15 to 20 minutes longer for you to drive than if you use the Disney buses. That is from the time that you catch a bus, so there could be some time waiting at the start. But bus lines to the Magic Kingdom are typically pretty reliable and timely.
With a tired child that can be a lot of extra time getting to the car, buckling in, cooling the car down, driving in traffic, finding a parking spot, getting back to the room, etc. So for me when I go to the Magic Kingdom I typically choose the following;
- If I am staying at the Contemporary, Grand Floridian, or Polynesian, of course I just monorail home
- If I am staying at Fort Wilderness or the Wilderness Lodge, I boat home.
- If I am staying anywhere else, I take the bus
So that is my recommendation. But if taking your car makes you feel more comfortable, it is not a bad choice either.
I hope that this helps?
Have a magical vacation!