Hi Megan,
Welcome back! My friends have asked me that very question numerous times, and my answer varies depending on the age of your children.
Mickey's Not-So-Scary Halloween Party and Mickey's Very Merry Christmas Party are my favourite events at Walt Disney World Resort, however, I do find that if you have really small children who need to be in bed early, the events may be better left until they are a bit older and able to enjoy the celebrations. (There are fabulous options for child care at Walt Disney World Resort, if that is something that you would need as well so the rest of the family can enjoy the party).
Here are my reasons why I believe that Mickey's Not-So-Scary Halloween Party is worth the extra money:
1. The Magic Kingdom is significantly less crowded during party nights, which means shorter lines and more chances to ride popular attractions with minimal wait times.
2. One word: CANDY. It is quite an experience trick-or-treating in the Magic Kingdom.
3. There are many different character meet and greets during the party, and the lines are again, significantly shorter.
4. The parade and fireworks are Halloween themed and completely spook-tacular!
Please let me know if you have any other questions Megan. I hope you have a magical time on your Walt Disney World Resort Vacation.
Stephanie