Hi, Diana!
I would definitely spend my one day at
the Magic Kingdom theme park. It's a great combination of something old, something new, a great parade, and fireworks, too.
There are classic attractions, like
Pirates of the Caribbean and
"it's a small world" mixed with newer favorites, such as
Under the Sea - Journey of the Little Mermaid. There is a great show that takes place a couple of times daily in the castle forecourt, and the
Festival of Fantasy Parade, which gives you a street-side seat to a celebration of some of your all time favorite Disney stories.
There are way too many attractions to list, but the whole night culminates with the
Happily Ever After Fireworks Display. It's like the cherry on top of the sundae.
If you can score a reservation at
The Crystal Palace, you'll enjoy an awesome buffet meal at breakfast, lunch, and dinner, plus, you'll see some of your most beloved characters from Winnie the Pooh. Or, for breakfast and dinner, hop on the monorail over to Disney's Contemporary Resort for a meal with the characters at Chef Mickey's.
I hope you have a magical time with your son, Diana!
Anna