Hi, Amanda!
How exciting!
If you are here asking Disney Parks Moms Panelists for advice on which Walt Disney World book to buy, of COURSE I'm going to have to recommend Disney Parks Moms Panelist Doug Ingersoll's book,
The Complete Idiot's Guide Walt Disney World. (It can be found on Barnes & Noble.com, among other sites.) You know that the advice in that book is going to be top-notch, as Doug is a well-respected Panelist, Disney enthusiast and Dad. I love my copy!
Regarding the must-do parks? If you can visit all 4, be sure to do so. There are spectacular elements at each location, including attractions, shows, fireworks and dining opportunities, so be sure to plan out a schedule which enables you to visit all four parks. Because Disney's Animal Kingdom closes earlier than the other parks, plan to spend some time at Downtown Disney on the night of your AK day. I'd be happy to send you a suggested itinerary including your family's Must-do list if you send me another question including information such as if you'll be on a Disney Dining Plan, your resort, family favorite characters / movies and dining interests. I can send you ideas for your son's big day, too. Just let me know the date!
For must-dos? I suggest that you check out "Must Do Disney: Disney World In Room Park Preview Video (Stacey)" on YouTube. For Disneyphiles, this in-room video is a highlight of checking in to a WDW resort. Once you hear Stacey on the TV in your WDW resort, you know you're home. Tips include attractions, entertainment and options such as
FASTPASS, too.
Happy planning, Amanda! Remember to send me more info.; I'd love to help!