Hi Patricia,
It's so wonderful that you and your husband are bringing your little ones to Walt Disney World for a family vacation. They are sure to have an amazing time. For the ages of your children, each park will offer a memorable experience. I would suggest dedicating 1 day per park, which will give you ample time to explore and pick your favorite attractions.
As mentioned earlier, each theme park offers attractions and experiences for little ones of all ages. When our almost 4 year old girl was around the age of your son, she really enjoyed Magic Kingdom and Animal Kingdom. Magic Kingdom is the prime theme park for kids of all ages, since it's filled with lots of character meet-and-greets, shows, parades, and attractions that the whole family can ride together. You'll have to take your princess and prince to New Fantasyland. Enchanted Tales with Belle and Under the Sea ~ Journey of the Little Mermaid are favorites of both of my kids. Be Our Guest restaurant is truly magical, whether you stop in for lunch or dinner. When it comes to Animal Kingdom, you'll have to set aside lots of time to spend at DinoLand U.S.A. Our whole family had a great time exploring the attractions in this part of the park.
One great tip that our frugal family uses to save money on food is to
buy Disney gift cards ahead of time. It's an easy way to allot a certain amount towards meals in the park without the risk of going over budget. Before we added the Disney Dining Plan to our vacation package, we would buy a gift card for each day we'd be visiting the parks, and included a bit of money to use towards souvenirs as well.
I hope this answered your question. Patricia. If you have any other questions about your upcoming vacation, please feel free to ask us at any time.
Have a fantastical Disney day!