For me, I read the unofficial guide, the Birnbaum official guide, TourGuide Mike, and many different boards. I would recommend both because the more information you have, the easier it is for you to change your plans as events unfold. I had a basic plan together of what we intended to do. However, if it rained for part of a day, or something came up that someone really wanted to do, I was able to adjust based on all the great info that I had.
TourGuide Mike does have some awesome info that I didn't find anywhere else. If you didn't do anything else, the money for his site is well-spent. You do have to be prepared to read and digest the info.