Disney - the park of dreams.
I highly encourage you to spend a lot of time at a particular park and pay attention to the detail. If you slow down and look at all the detail crammed into the Disney parks, you'll find that the parks really aren't just for kids.
If you have a 4 year old with you, I'd stick to Animal Kingdom and Magic Kingdom. They're the most kid-friendly parks out of the four.
http://www.galttech.com/research/travel ... ingdom.php http://www.laughingplace.com/Info-ID-WD ... tGuide.aspMagic Kingdom gets really crowded at night - that's when the fireworks and light parades begin. The morning and afternoon are your best bet to beat the lines.
Tony's is a great place to eat with a kid - it's themed to the restaurant in Lady And The Tramp. If one of you is having a birthday, don't forget to mention it to the waiters at Tony's. You'll be in for a treat!
Animal Kingdom is a less-popular park compared to Epcot and Magic Kingdom. You'll find that there are less crowds in the morning and around lunch time.
Go to the Lion King show with your kid. Both of you will fall in love with the performance.
Hollywood studios isn't the best place to take your kid, but you will definitely love it. Keep this park in mind when he gets older!
Epcot is my personal favorite park. You won't want to miss the fireworks show - it's spectacular. There are a few things that your kid will enjoy, but this park is mainly for sci-fi lovers and technology enthusiasts to put it simply. Fantastic and beautiful park.
Magic Kingdom in May on a Sunday afternoon - busy. Not as busy as Saturday afternoon, but you should still expect some large crowds. My advice to you is go very early when the park opens and try to experience a lot of rides before the crowds take over. Then I'd go to Animal Kingdom and walk around - your kid will love the animals. If you have time, maybe try to stop by Epcot. End the day with fireworks from either Magic Kingdom or Epcot (preferably Epcot).
I can't stress enough the excitement of studying the detail in each of these parks. You will be surprised at how much there is, I can guarantee you that!
Best regards,
billcollins531