Welcome aboard, Heather! What an exciting fall you have to look forward to with a cruise on the Fantasy! I checked in with Disney Cruise Line and they haven't set their Halloween plans for this year just yet, so I can't give you any specifics right now.
However, take a look at the Disney Parks Blog from last October about
Halloween on the ships. The late October sailings offered some exciting Haunted parties, spooky movies, ghoulish delights and special Halloween merchandise. Characters were decked out in their own Halloween costumes too! What a great chance for photo opportunities. Over Halloween itself, the ships have usually had some sort of Trick-or-Treating event too. Perhaps this October will see some of the same. I bet that will take place on the Fantasy's October 26th sailing for sure since it will be over Halloween, but if you're travelling on the October 19th sailing, you might just be treated to some spooky surprises then too!
Keep an eye on the Disney Parks Blog as your sailing gets closer, as they are usually among the first to announce these exciting events on the ships.
The Princess Gatherings usually take place two times, and usually on at-sea days. We arrive about an hour ahead of time and are among the first couple families in line. I bring postcards for my kids to sit and write to friends and family back home to help pass the time. We are always glad to have arrived that early when we see the long, long lines behind us. No matter if you attend the first or second (though check to be sure there WILL be a second one!), arrive early and you'll be all set.
Have fun as you continue to plan, and please let me know if I can help with anything else!