Hi Ilaxi,
Your little Prince will have an amazing time at Disney World. There are so many attractions he can enjoy even at the age of three.
A large majority of the attractions at Disney World are slow moving vehicles which can be enjoyed by any age. On a good majority of the attractions your son will be able to sit right next to you in a seat or bench. A great place to check for information is
www.allears.net under the Theme Park option. You will be able to see a list of the few attractions that have height restrictions.
Given his age I would be sure to spend a good deal of time at Magic Kingdom. This park offers the largest number of family type attractions, and a great place to start is Fantasyland. Some of my boys favorites at that age were Dumbo, It's A Small World, Peter Pan's Flight, Buzz Lightyear Space Ranger Spin, The Many Adventures of Winnie the Pooh and Pirates of the Caribbean. Don't forget there are also quite a few cool shows that are family friendly for all ages. Our favorite at Magic Kingdom is Mickey's PhilharMagic.
If your son enjoys Playhouse Disney, you want to be sure to schedule in some Hollywood Studios time. There are some great live stage shows here including Playhouse Disney, Voyage of the Little Mermaid, Beauty and the Beast and Indiana Jones Stunt Show. There is also a very cool Muppets 3D show at Hollywood Studios that our boys love.
Be sure to schedule in some time to meet the characters and get autographs.Wishing you and your prince a magical time!