First, don't try to do it all in one visit. It's just not possible and you will get exhausted. Planning is key, pace yourselves and take in a variety of what WDW has to offer. Then, you can hit other spots on your next visit!
Get a few good guides such as Frommer's, Birnbaum's and the Unofficial Guide to WDW. Each has a different take on things. Then make good use of sites like this one and ask questions.
If you are a newbie to WDW, you must at least visit each of the parks. Give yourselves at least a day each at the MK, DAK and MGM and two days at Epcot.
At the MK, take in the classic rides such as Pirates, the Jungle Cruise, Haunted Mansion, Small World and even Dumbo. I'd say, do these first to get a feel for the beginnings of Disney's theming and technology. Then if you have time see the Hall of Presidents. It's the next generation of audio-animatronics. After that, enjoy the "mountains" as well as the kiddie rides, parades and other amusements. Be a kid, nobody will laugh at you.
MGM has marvelous rides as well as stage shows which should not be missed. Here you will get a feel for Disney as a production company. The Magic of Disney Animation is one attraction that I love since it gives both history and live demos (when you go during working hours) of the process involved to create an animated film. On the Great Movie Ride watch as the new generation of audio-animatronics entertains you.
DAK is a park still growing and ever changing due to its theme. This is a park you must take your time with to enjoy. Animals go at their pace. Talk to the CM's there who are very knowledgeable and willing to offer advice and info.
Epcot is a joy. There is a surface splash of activity and color. There are also hidden treasures to be found and that takes time to find and savor. I suggest two days (minimum) so you can devote a day to each half. In Future World, play and explore the universe and life in it's many aspects. Set your imagination free, venture into the inner you on Body Wars then the outer universe of Space (just do it before lunch). Play with everything from water to high tech toys. Another day, explore the World and it's cultures in World Showcase. Don't forget the shows held in each Country. Chat with the CM's in each Country, who often come from regions within each. They are some of the best guides to what you are experiencing.
After the parks, leave yourselves some time and energy for other attractions such as Pleasure Island, a water park or two, Resort tours, sports, etc. WDW is HUGE and truly offers something for all ages.
Enjoy it!