My kids love the World Showcase but, I'll be honest, it takes a bit of advance planning to pull it off. You have to, have to, have to keep an eye on the entertainment schedule. You'll get an Epcot Times Guide but you can do a bit of advance research by clicking on the "Epcot" button at
http://pages.prodigy.net/stevesoares/ you can also use this site to plan your character meet & greets.
And a trip to Disney World is supposed to be a "family" vacation - that means that you, as part of the family, should be able to enjoy the World Showcase - it is just one afternoon out of the whole trip. The first time, I told my kids, "You are free to enjoy it or not enjoy, that is up to you. But you are not free to whine at me about it - the other option is to cut our vacation short by one day."
Here is what we like:
Your four year old will enjoy the hedge maze at the UK pavilion, it may be too small for the 9 year old. British Invasion is fun beatles type music - extra fun after dark, I think. The World Showcase Players jokes will probably go over the kids' heads but they'll probably enjoy the silly antics of the skit.
Canada - "Off Kilter" is great fun - bagpipe Rock & Roll, might be too old for them although we bought the CDs and my 9 year old loves them. I'm not a big fan of the circle-vision movie at this pavilion. If you are going to do a circle-vision - the China one is more interesting.
France - the "Serveur Amusant" act is a balancing act. My kids were pretty impressed.
Morocco is just plain fun. There are almost always characters from "Aladdin". It is full of nooks & crannies with fun things - kidcot, drums, interesting shops. "MoRockin" is a Middle Eastern Pop group, often with a belly dancer. My 9 year old plays violin so the fact that they have a violin player was a neat thing for her.
Japan - "Matsuriza" is a drum act that a lot of folks really like but what we LOVE is "Miyuki", the candy artist. Get there at least 10 minutes prior to her scheduled performance and position your girls close to the cart where she does the demonstration. They may get selected to choose a color and animal to have made into a lollipop. If so, they'll get to keep it (free). My girls have gotten to do this twice and it is always a highlight. I particularly like the Swan and the dragons (although I usually hate dragons). There is also a Japanese Storyteller but we haven't heard that yet. When we were there, there was a little museum type exhibit of pressed tin toys that we enjoyed even though we passed through pretty quickly. There is also a pond with Koi fish. The Yakitori house is a great place to eat after dark - take your food out to the area with the lanterns. There is just something special about it.
America - well, if you are there when it is hot, the American Adventure show is a great place to catch some A/C & maybe a nap. But there are funnel cakes and, as Martha Stewart would say, "It's a good thing."
Italy - the Living Statues mentioned in an earlier post are no longer featured here. The World Showcase Players do a cute skit called "Romeo & Edna". There is another act - a juggler, I think. But we haven't seen it yet.
Germany - kids always love the model train.
The Outpost is in here somewhere and the African Storytellers always come highly recommended but we haven't seen them yet. They're only there Mon - Friday.
China - Kids always love the Dragon Legend Acrobats because they are children too. On of my girls' favorite souvenirs was to have silk fans personalized with their names written in Chinese. The fan was only about $5.
Norway - there is a Viking boat play area and yummy treats in the shop. Maelstrom has trolls so it can be a little scary for your 4 year old. Princess meals available for Breakfast, lunch & dinner.
Mexico - the Mexico ride is hokey. The San Angel Inn is a neat restaurant.
Another fun thing - exit Epcot through the International Gateway and go to "Beaches & Creme" over at the Beachclub resort. You can easily walk or take the boat. B&C is an old fashioned soda shop style restaurant with burgers and ice cream treats. It is very cute.
There are two entertainment options at Future World that I would like to recommend - Kristos is a Cirque du Soleil style balancing act and Jammitors is a Stomp style percussion group that our kids enjoy.
World Showcase seems to be the place that our family really interacts at Disney World - we stroll along, eat, and talk about what we liked and what we didn't.