I have found the unofficial guides to be a great resource. I like that each attraction is rated for different age groups - preschool, elementary school, adults, seniors, etc. That info is on the DIS if you search or ask people if a ride is appropriate for a particular age, but I like it all together in the UG. I usually get the UG Mini Mickey - it is travel-sized. There is also a full-sized version.
The touring plans can also be very helpful if you are a first-timer or are going at a busy time. The book explains how each ride loads (e.g. Dumbo or Cinderella's carousel - everyone gets on and rides, everyone gets off, a new batch of people get on, compared to Pooh or Peter Pan where ride vehicles are constantly being emptied and filled). You can pick up many of the tips here (ride Dumbo first - it doesn't seat very many people and the ride gets longer and longer as the day goes on, use Fastpasses, etc.). Like the PP said, the books travel - you can read them in the car pickup line at school, on the ride down (if you're not the driver
), during your child's soccer practice, etc.
I have not used the Passporter for WDW, but I have one for
Disney Cruise Line - it has a wealth of info and pockets to organize things, etc. If you carry a backpack into the parks, it is great to stick in there and have all your confirmation numbers, dining times, etc. where you need them. I don't carry any more than I need to - I used to photocopy a few pages of the UG, but I don't do that anymore.
If you have a Barnes and Noble near year, pick a few off the shelf and look through them to see if they look helpful. You can also check your library for guide books - they might be last year's, but most of the info is the same.
). I own Birnbaums for kids, UG, UG with kids, Idiot's guide and Passporters. I like the UG and Passporter's the best. They all have different info and it's all presented in different ways. 
, so something on paper was a must for me. Both times that we have gone, I bought the PassPorter (from Barnes & Noble) and was soooo glad I did. It definitely helped us with schedules (even though we're pretty flexible) and especially with our meal plans. I bought other guides for our first trip, but soon found that I was relying totally on the PassPorter. The DIS was especially useful for those extra little questions that come up during the planning. Without this board, we would have missed out on a lot! 
