I've been to Disney many times. Tons of times as a kid, and to look back at it, we had our own way of touring that we learned from experience...
Now as a mom myself, I have to say the pre-planning is sooo helpful. Our first trip with the kids, I planned everything...and our plans changed multiple times a day. Luckily, we were there between hurricanes, and after most schools had started (late Aug early Sept). So changing our plans didn't matter...we were able to make new ADR's etc.
Then next trip I planned a little less...okay, not really...but we actually stuck more to the plan...allowing of course for the changes that were necessary. (The kids did a lot of swimming this trip...but they were happy).
I say plan plan plan, but when you get there, remember to have fun. Sometimes letting go of some of the plans is okay. I remember telling DH that I wanted to hit as much as we could b/c I didn't know when we would get to come back. He would remind me that the kids were happy with what we had already done...they didn't care what else there was...(ignorance can be bliss)...when I realized that he was right, it was easier to let some of the plans go.
That said, our next trip will be around Christmas, and I am already planning!!!
Good Luck!