Hi, Denise! Congratulations on your first visit to WDW! That's a tough decision on whether or not to pay the extra for tickets to
Mickey's Not-So-Scary Halloween Party versus stick with the plans that are already included in the price of the vacation.
In terms of the experience, nothing compares to the Magic Kingdom's MNSSHP with the special parade and fireworks, trick-or-treating in the park as well as the one-of-a-kind character greetings, dance parties and extra time on the most popular attractions. Yet, it
is an added expenditure that you may have not planned.
Besides Illuminations, what else do you have planned for the evening? Any special dining or experiences, and do you have plans to visit Epcot at another time during your vacation? If you already have another day set aside for Epcot, I wouldn't worry too much over just missing Illuminations. Although it's pretty cool, it's the least impressive end-of-the-evening park entertainment.
Epcot would be a more "grown up" evening whereas MNSSHP would be great fun for everyone! Let me know if I can answer any other questions you may have. Have a wonderful day and a most magical vacation!