Man alive, I had never seen it so empty in my whole life. Well, you know....empty for Disney World. It was my wife, our two year old daughter and myself (oh and plus the in-laws). We all had such a great time. Almost every ride in Fantasyland was a five minute wait. And that was only because it takes about five minutes to walk through the queue (especially with a toddler). I walked onto every ride. I even got to ride some rides I wasn't planning on riding just because there was no wait (like Splash Mountain).
I also think the staying hydrated issue cannot be stressed enough. Especially if you are a Bostonian like myself and are walking around Orlando in 95 degree humid air. Dehydration can overcome you quickly at a themepark because you may be distracted and unaware of it. Which is why we tried to drink and drink often.