For many of us that enjoy the food, we must sometimes make ADRs months ahead. So that drives where we will be many of the days.
Off season, we check parade, fireworks and evening show schedules and make sure we are where we need to be for those with limited schedules... and we plan to be there early in the trip in case we change our plans or the weather changes them for us.
I also look at which parks have early opening. If we are going early, we go... if we are not, we avoid the parks with early opening. We fill in our schedule with special events if any, like DVC events, and the rest we decide day by day.
This year our daughter is almost 7 and old enough to help plan. So we've been through all rides and she has told us what she wants to do..or not do... and we would set expectations about height restrictions except she has no interest in any of the ones she is too short for anyway!
I have a daily schedule grid with park hours, early and late hours, etc. for each day. with our ADRs filled in. I have a page for each park with attractions, character greeting locations and times, and show and entertainment times in one east reference. I have a page with my dining plan reference and another with my DVC discounts. These all fold up and go in my pocket in case I need them.
I spend hours and hours planning in the months, weeks and days leading up.. it's half the fun for me.