Hi Lindsay,
While crowds can vary depending on the night, both Mickey's Very Merry Christmas Party and Mickey's Not So Scary Halloween Party have a maximum number of Guests allowed, so crowd size should be pretty similar between the two events.
If you haven't ever experienced
Mickey's Very Merry Christmas Party, I highly recommend it! It's my very favorite special event of the entire year. With low wait times for attractions, special Character greeting opportunities, gorgeous decorations, festive music, complimentary snacks and treats, snow on Main Street U.S.A., the amazing Holiday Wishes fireworks show, and my very favorite...the Once Upon a Christmastime Parade, you'll find this event to be jam-packed with magical moments! If you loved
Mickey's Not So Scary Halloween Party, I'm confident that you'll love this event, too!
You are correct that Christmas break is a very popular time to visit, but
dates were recently released for both of these special events and you'll find that Mickey's Very Merry Christmas Party begins on select nights in early November. While Thanksgiving week is another really popular time, visiting during the rest of November or early December should be comparable to what you'll find in October regarding crowd sizes and wait times.
The great news, Lindsay, is that you can't go wrong visiting during
either of these special events! They're both magical in their own way, and I hope that you make memories to last a lifetime at whichever one you choose!
Missy