The most important factor is to sit with your family and decide how long you should spend at Walt Disney World theme parks in Orlando. If you are going in a big group then you have to understand that not everyone may like to go to the same park(s). If it is small group (may be 6 or less) then things get a little bit easier. So decide the number of days you want to be at Disney World considering that each individual in your travelling party gets to spend a fair amount of time at the park he/she likes.