For myself, I have a spreadsheet.
For my family, I make a book before we leave (in hopes of not having to repeatedly answer questions) -- I snapshot the Itinerary page from
MDE for each day of our trip -- this has park hours for the parks we have FP in and also says our current resort location for the day including check-in and check-out days (for a split stay) it will say Check out of _____ / Check in to _________. It also has any applicable confirmation #s, which is nice because if desired you can just grab the page on your way out the door in case anything goes wrong when checking in for something.
At the top of the page I put the date, followed by an overview of the day's plan that includes relative strenuousness compared to day before and after (comments like "busy day today, but no worries, some major relaxing time tomorrow" or "after dinner at 6 we should make sure not to stay up too late because tomorrow we have a full day", and other "color" details. This is usually about a paragraph or so total. Then I put the itinerary snapshot, then if there is a touring plan I put a few lines of description ("this plan is aimed mostly at covering Tomorrowland and Adventureland in the Magic Kingdom; since we'll be arriving at Rope Drop most of our stops are in Tomorrowland early, then we'll be using FP in Adventureland after lunch mixed with some air conditioned attractions to escape the early afternoon heat"), then a snap of that, then snaps of any applicable menus for CS or TS that are in the plans. Obviously this covers a few pages / day by the time you're done with all the snapshots. I print it out for on-the-plane anticipation reading, but you could just as easily email it out.
I could just print out the spreasheet, but then I'd end up having to explain the spreadsheet ...