I think last Sept. was one of our best trips. The smartest thing we did was build in enough down time so that none of us was too tired or grouchy.

We also didn't let the dining plan run our trip like we did two years ago. We made the meals fit into what we wanted to do and we were even able to rearrange a few ADR's during our trip when we realized they weren't going to work out. We were also willing to lose some meals if they interfered with our fun!
Basically, we planned very well in the months before the trip, but then relaxed and stayed flexible once we got there. Also, I printed lots of tips from these boards and took them with us in a notebook, so I didn't forget the little things. And those little things really made our trip special. Those details are what makes WDW different from other theme parks.
Also, we stopped to talk with CM's more often, and have even developed a little friendship with one of the ticket takers at MK. She recognizes us every year and last year we spent a little extra time talking with her. She even showed us pictures of her grandchildren.

Talking with CM's is part of the magic for my little 9 yr old extrovert! The pin trading was a huge part of that.
I guess being lucky enough to have a 10 night trip and getting the free dining plan is part of what enabled us to relax on this trip, but it also took a little determination!