My wife and I have taken our son to Disney World twice in the past 4 years.
Rent a car, ends up being way cheaper in the end plus gives you the freedom to explore in your downtime.
Pick and choose what you really want to do. The first time we went there we tried to do it all and it got stressful to the point of almost not being fun. If you find something that everyone is having a good time at, don't rush to leave it just because you have to hit this or that park.
Plan a day of downtime. We scheduled this right in the middle of our trip. It was nice to not have to run anywhere and sit at the pool and relax. Running around and being around mobs of people all the time takes it out of you, you will need time to recharge.
If you have a chance and like seafood, go to salt island. They bring in fresh fish everyday from the coast. -
http://saltislandrestaurant.com/ Somewhat spendy but my favorite resturaunt in Orlando.
Have fun on the trip!