Most people would say my laminated Itinerary cards would be over planning but it works for us so everyone isn't looking at me saying "where do we go now". I have the rides/attractions listed in order with an "estimated" time and our fast passes noted (moms don't go on bigger rides so we get use their bands to maximize the rides for us). On the back I print the map from touring plans so everyone can find their way to the next ride if they get lost.
Traveling with our 2 moms and 5 year old twins, I try to keep walking down to a minimum so we aren't crossing the parks and our plans are made up until our lunch time afternoon break back to the hotel. Our evenings are mostly left free based on everyone's energy level.
2 years ago our biggest wait was 30 minutes during spring break and that was for Haunted mansion and we didn't have Fast Passes for it. Hoping for the same luck this year. Over planning before the trip allows us to not have to stress about what we want to see when we are on vacation.