Hi, Oded! EPCOT is my teenage daughter's favorite theme park, and she could easily spend two days visiting. It will, however, depend on how much you want to see and whether or not you are going during a peak vacation time.
Some attractions your teens might be interested in include Test Track, which is a fast ride that takes you through the paces a test car might go through; Mission: Space, where you take a simulated journey to Mars; and Soarin', where you seemingly glide by hang glider over some of California's most amazing scenery.
My daughter loves to see the shows throughout World Showcase, including Off Kilter (a Celtic rock band); Mo'Rockin (a rhythm infused band with a Moroccan flair), and the comedy troupe in the UK section of the World Showcase.
I would check out the information on the park by visiting
HERE. You can see which attractions most interest your children, and determine how long you think you might need to see everything. I like to list must do things first, then the things they would really like to do if time permits. Don't forget to allow time for food! EPCOT has some of the best dining anywhere at Walt Disney World!
Enjoy your vacation!