Depends on what your children enjoy. You know them better than we do!!!
Do they like thrill rides?
Do they like live stage shows?
Do they like parades / fireworks?
Do they want to meet the Disney characters?
You're not going to get great answers just by asking on a message board with so little info provided. My recommendation: either sit down with them in front of your computer and spend a few minutes browsing Disneyworld.com, or buy a copy of the Birnbaum's WDW vacation guide. The web site now has great info on most of the WDW attractions, which should allow you to highlight the ones that really catch their eyes. If that doesn't work, try the Birnbaum's book. It won't give you as detailed information as you might find in the Unofficial Guide to WDW (which is about 700-800 pages long), but it does give you a colorful overview of the entire park including all of the rides, restaurants, shops, etc.