Woohoo, Disney World!!! Wish I was going!
Let's see- personally, with a 20-month-old, I'd probably skip EPCOT. If he is particularly wild about fireworks, you might be interested in going just for that, but my daughter was scared to death of them, and was happy watching from afar. Animal Kingdom is awesome. If you think of it as a zoo and not as a theme park, you'll be blown away. Try to take your time and not rush off to the rides. I wouldn't take him to see It's a Bug's Life, as it's surprisingly scary. But there is a very fun playground in Dinoland USA (in Animal Kingdom) with a dinosaur dig that would probably thrill him for hours.
MGM really only has one thing going for it, especially for the smaller ones- the Toy Story Midway Mania. The other rides and exhibits are really kind of boring for the kids.
Magic Kingdom- oh, just try everything! My daughter loved it's a small world when she was 3. There's Tom Sawyer's Island that you have to take a raft over to, but then it's all exploring, so he might like that. I can't remember if the Dumbo Ride is closed right now, but I think the Carousel is open, and the line goes very fast. The People Mover is a surprisingly fun thing to do when you need to sit down. He's probably too young to participate in the Space Ranger Spin, but not too young to appreciate it. He might also like driving the race cars. I think Toon Town is closed (bummer). I'd avoid Pirates of the Caribbean unless your son is super-adventurous. There's not really anything scary, but they don't know that, because it's dark and spooky sounding. Ditto on the Haunted House. Flying Carpets is just as much fun as Dumbo with a shorter line. My kids didn't care for the Snow White ride.
Last time we went, my 21-month-old nephew was absolutely BONKERS about the Main Street Electrical Parade- I have videos of him dancing his little heart out. The fireworks are always fantastic, but again only if he's a big fan. Otherwise, consider hopping on the monorail over to the Polynesian and watching the fireworks from across the lake. Still very pretty, and they pipe the music out on the beach so you can still experience it.
Meeting characters- we usually take an autograph book for the characters to sign. My nephew didn't care about the book, but he sure loved meeting all the characters.
One other thing about EPCOT- it's Food and Wine Festival time right now, and you can use your snack credits to sample the wares. I know I said not to go to EPCOT, and I really mean it, but if you want to go out one night without your son, this is a fun thing to do.
Take advantage of the Extended Hours for on-site guests. The crowds are significantly smaller at those times.
Gosh, so much to say. Really, you should check out www.allears.net if you haven't already. They have menus for all the restaurants, park hours, parade schedules, resort maps, ride closings, etc. Very helpful. And I know I sound like a Disney nut, but that's because I AM a Disney nut!
Have fun!
