Where's all the fun stuff is a broad query in the context of WDW. If you get 100 replies on this forum, you're likely to get 100 different answers !
If you want to plan for a really great trip and make the most effecient use of your time while you're there, you really need to begin planning for it well in advance. I say at least 6 months and if it's your first visit, a full year ahead isn't too early.
You'll get some of the best advice and reviews you can find from all the wonderful people here on WDW Magic, but if you really want in depth information that can't be beat you need to hurry down to the book store or visit Amazon.com and buy two books.
The first is
The Unofficial Guide to Walt Disney World 2007 and the other is Birnbaum's Walt Disney World 2006 .
Then sit down and read them cover to cover, and start over and do it again. you'll be glad you did.
You can get both books here :
http://www.amazon.com/Unofficial-Gu...ef=bxgy_cc_text_b/102-1841841-2572122?ie=UTF8