MNSSHP is a blast! We've done both MNSSHP and
MVMCP and IMO MNSSHP is the best. Christmas is my favorite time of year but the Halloween Party was a lot better than the Christmas one. Our MNSSHP plan goes like this:
1) Dress up (yes, even the adults, it's fun!)
2) Be at MK at 4:00 (they will let you in early with your hard ticket)
3) Grab a locker (free for MNSSHP)
4) Ride Haunted Mansion and Pirates of the Caribbean and anything else if time permitted before ADR
5) Eat at LTT (need ADR) around 5:00ish (the characters are dressed up in their Halloween costumes)
6) Get pictures made. We dress as pirates so we get a lot of pictures made in and around Pirates of the Caribbean ride.
7) Get MNSSHP T-shirts at the Emporium but while getting there, stop at every Trick-or-treat spot along the way.
8) Go to locker, get change of clothes and wear MNSSHP T-shirts.
Then enjoy the rest of the evening partying, and don't miss the parade!
We change after pictures because our costumes are thick and heavy therefore very hot, but do ride some rides in costume before changing especially Splash Mountain where they take your picture

...very cool.