We never plan. We find out every little thing we can find out. We find out the facts, the strategies, the contingencies, the bargains, the times, the hidden fun, the opinions, and so on. Well, I find it out, and the wife trusts me.
That way, no matter where or when we find ourselves, we can make the best of it.
We NEVER plan what parks to go to on what days. I mean, I make a chart of park hours, parade/fireworks times, Extra Magic Hours times, and so on, but it's an INFORMATIONAL chart, not a list of what we must do. It informs us. If we want to see Fantasmic, for example, we know the two or three days during our week that we can choose from, and so on.
We make one or two ADRs, and no more. And we HATE those days. We HATE the idea of having to be somewhere at a certain time during vacation ... too much like every other day of the year to us.
The way we pretty much decide which parks on which days is to ask the kids either the night before or the morning of. We did this even when the kids were 5 and 2 (they were almost 9 and 6 on our most recent trip last year). THAT usually makes the uber-planners' heads explode.
Because we know all the information and all the strategies and smart moves and stuff like that, we always have a great time, we always do everything we want to do, and we never have any regrets, just fun!