Hi Ashley!
I am from Garland (just outside of Dallas) and a fellow Disney lover. We went last December and are planning a trip to return in October 07 (I wish we could go this year like you are, lucky ducks!).
Don't miss Mickey's Not so Scary Halloween Party! It is a separate event in the Magic Kingdom at night, your son will LOVE trick or treating with Mickey.
I have a DS who is also 6! He had a blast too. We will be celebrating his 8th birthday riding Test Track 8 times (that is what he wanted for his birthday, we'll see if I can handle it!).