I think some sort of guide book is essential, but we each will have our own preferences as to who's the best. I think I have read every single book out there...it's it printed, I've read it!
IMHO, the Unofficial Guide & Tour Guide Mike are two of the best. Although, TGM can get pretty complicated, trying to navigate everything on his site!

Birnbaum's, to me, was more 'pretty' with all of its pictures, but I felt like the advice it offered was pretty simple and basic.
Do I follow their suggested itineraries down to the minute? Heavens, no! But it definitely helps give you a plan of action....
I think, if you DON'T read the guide books, you are one of those poor souls who show up at Mission: Space or Test Track at 11:00 am, and gripe about having to stand in line for 90 minutes. Those of us who read the books - we've already ridden those rides several times, and have MOVED ON!!!
Also, in reference to the comment about most guide books suggesting to ride the rides before 10, or after 6, leaving nothing during the bulk of the day, that is a GREAT time to go back to your hotel room for an afternoon swim or rest....No matter HOW old you are!!! The late afternoon & evening will go so much better if you're fresh and relaxed!!!
