Hi Michelle! Making a visit to Walt Disney World in the fall is a great time as there is so much happening in the parks and around the resorts.
The great
Mickey's Not So Scary Halloween Party is one of these fun experiences. Beyond the night time attractions you will also enjoy the trick or treating, special character meet and greets, and definitely the awesome Halloween parade and fireworks. Halloween night is certainly one of the most crowded nights and they will sell out quickly for the tickets so if it is something you will consider doing it is important you purchase your tickets fairly soon after the dates are announced which should be soon.
I always recommend that guests who wish to head to this party consider going to another park or enjoy your resort pool for the day. When you purchase the party ticket you can enter as early as 4pm to the Magic Kingdom simply using the party ticket. That would allow you into the Magic Kingdom to do some attractions before the party officially begins at 7pm. You can then enjoy some trick or treating and the parade and fireworks and head home.
If you plan on just doing the Magic Kingdom during that day then it will be a long day for the kids. Being tired when you begin the party is not going to be as enjoyable. With the added cost it gives you pressure to stay and do as much as possible even if the kids are done!
The resorts will not all offer special activities such as trick or treating. Fort Wilderness is the one official resort that has a huge evening in store for its guests. The RV loops are open for trick or treating and it is quite a sight as so many of them also decorate for the holiday. The kids can leave with plenty in their bags while the parents enjoy the ambience and decorations. Other resorts might offer something simple but it can change from year to year.