For my family, a successful Disney vacation (or any vacation for that matter), is one where everyone enjoyed themselves. Simple. We don't measure that in hours, time in a park, money spent, etc. There is no number attached to it. Our vacations are not regimented, we don't keep schedules (unless we are on a cruise or other vacation, and have a tour scheduled). We make sure everyone gets a say in what we want to do. That is how we create a successful vacation.
It's not hard to find a middle ground, you just have to want to do so. You haven't even asked the woman if she wants a trip (and I would not want one with strings attached or a pricetag held over my head), and you are already assuming she will make a mess of things.