Reporting back for reference:
We went to the Sunday-before-Halloween, Halloween, and the day after Halloween parties. All of the party specific food was available. Adventureland/Pirate Radio was still playing. There were no special events, different magic shots, or changes to the party vs. when we went in August. We were surprised to find a lot of Halloween Merch gone from the stores and replaced with Christmas, even before Halloween. Also, the Halloween Merch that was offered in Momento Mori, our hotel gift shop, Downtown Disney, and on Main Street was roughly the same.
We had a great time and did every ride we wanted to. On Halloween night, Haunted Mansion posted a 20 minute but it was a walk on. We didn't see the characters outside of Haunted Mansion any night except 10/29, but I was told that was just because they were 'on break' each of the times we went by. Lines for the Haunted Mansion magic shot were between 10 and 40 minutes, but other magic shots were zero wait. The longest ride line was Tron, where despite having a virtual queue, we would then need to wait in line at least an hour (and that was at 11:15 at night!).
Halloween definitely brought out the best costumes, but otherwise was not different in any way from the other parties. I was surprised by the number of people at the 11/1 party, the crowds felt worse than 10/29. The Space Mountain Overlay was just turning off the lights and sound. I was surprised that we weren't warned when we went in line at 6pm that they would shut down the ride for 20 minutes with people waiting (I expected them to close the line, get everyone out, turn on the overlay, then reopen the line).
FYI: there is no way to skip the candy and just watch the Halloween movies at the Philharmagic theater. We didn't want candy, but would have been required to wait for it and then walk past it to see the show. The castmembers were unable to estimate a wait time for the candy/supposedly there's no way to estimate any wait times for treat trails.
Having done Oogie Boogie Bash last year, and multiple parties this year, I might be burnt out. I was really surprised that Disney didn't offer anything special on Halloween. It felt like they were ready to move on to Christmas. We did get to see the Gingerbread house going up at the Grand Floridian, and had our choice of Christmas Merch, but as big Halloween fans... meh.