Hi Cheryl,
I remember being in Magic Kingdom Park when my daughter was a preschooler. It is such a magical age to visit Walt Disney World with your little one. The wonder and excitement in their eyes is truly amazing!
There is so much to do at Magic Kingdom Park for little ones that it might take you more than one day to cover all of the possibilities. However, this also will depend on how your family prefers to tour the Disney theme parks. When our daughter was 4 years old, we preferred to head to a theme park right when it opened, experience lots of attractions in the morning and through lunchtime, and then head back to our resort for a rest in the afternoon, possibly returning to a theme park in the evening. Keeping the afternoon nap for my daughter was necessary! If you plan to be in the theme park all day and into the evening, you might be able to do all of your Magic Kingdom highlights in one day.
I suggest that you take a look at the
Magic Kingdom Park attractions and entertainment and make a list of your must dos. To help you in doing this, I recommend that you order the
free Walt Disney World vacation planning DVD, on which you can see many of the attractions. Once you have decided which of the attractions you feel you must do, take into consideration how long you spend to be at Magic Kingdom Park on each day, and then decide if you need one or two days. My family tends to tour slowly so that we can stop and take in the atmosphere along the way, and with a 4-year-old, I would suggest on planning only a few attractions at most per hour. Do not forget that you will also have to account for wait times in your planning.
I hope that these thoughts are helpful for you, Cheryl! Please do not hesitate to ask if you have any further questions.