I have this really radical idea and it goes like this...it is a family vacation and YOU are part of the family. If you are doing stuff that interests everyone else, they can do Epcot with you...and they can do it with a good attitude.
Epcot is my wife's favorite park. When the kids expressed the possibility of being bored, she asked if they thought it would be more or less boring than staying home. You can probably guess their response. Three of my four kids ((ages 20, 14, & 9) really like Epcot. My 19 year old daughter isn't a big fan but there are things she enjoys there.
Mission Space is neat - take time to enjoy the activities at the end of the ride too. There are kiosks where you can send really fun photo e-cards to her friends (bring email addresses along).
Test Track is not a lot different than the way my wife drives our mini-van, or so the kids say. We all prefer this ride after dark.
Soarin' isn't thrilling but it is neat. Imagine watching the travel channel on an IMAX screen from a porch swing hung 20 feet up in the air. What's not to love about that.
Club Cool offers free soda samples from around the world - kind of fun.
Honey I Shrunk the Audience is a fun 3-D.
There is a "Stomp"-like percussion group that performs in Future World called Jammitors that we always enjoy. There is a techtronic band near Figment called "Cyber Groove" that we haven't seen yet.
As for the World Showcase - my non-Epcot daughter always loves eating at the San Angel Inn in the Mexico pavilion.
See the Circle-Vision movie in China, just for the experience. The Dragon Legend Acrobats are neat there. We're not huge fans of the Canada circle-vision.
My kids are not particularly enthralled with the movie in the France Pavilion or the American Adventure. They do like the Maelstrom ride in Norway. We won't ride with them in the Mexico ride. It is pretty lame - a little like a cheap "It's a Small World" so my kids ride with their hands up rollercoaster style and scream. They're usually not obnoxious but they're sense of common courtesy completely vaporizes here. My apologies to the other riders.
Other entertainment that all my kids enjoy - "Off Kilter" is a celtic infused rock group in the Canada pavilion. "British Invasion" is only fun if your daughter has been raised listening to the Oldies station - then she'll know the words to the Beatles songs, this is fun after dark. She may enjoy "The World Showcase Players" in the Italy & UK pavilions, unless her sense of humor is too sophisticated. We think they're funny. "Serveur Amusant" is a fun balancing act in the France pavilion. MoRockin' is pop music w/ a middle eastern sound in Morocco. We all love Miyuki, the candy artist, in the Japan pavilion - really impressive. Sergio is a neat juggler in Italy.
And IllumiNations is a great fireworks display.
I really hope you get to go to Epcot and that you all enjoy yourselves.