Having said that, I am a firm believer in giving kids exposure to music of all kinds, but especially orchestral music (what non-musical people call "Classical"). There are so many great "classical" pieces out there that I can use in October that aren't all about Halloween! I can teach so many musical skills and concepts through these pieces - minor modalities, rhythmic patterns, symphonic poems, incidental music, composer profiles, you name it!
Here are a list of my favorite "Classical" songs that I use in October, but really can be done any time of year:
1. "In the Hall of the Mountain King" by Edvard Grieg. There is so much material out there for this piece - lesson plans, listening guides, etc. This is a fantastic piece for teaching ta and ti-ti (quarter note, paired eighth notes) and tempo!
Some helpful links here: http://www.makingmusicfun.net/htm/f_printit_free_printable_worksheets/mountain-king-listening-map.htm (printable listening map)
http://www.classicsforkids.com/teachers/lessonplans/pdfs/grieg/Grieg%20Lesson%20Plans%20K-2.pdf (lesson plan and materials for grades K-2)
http://www.classicsforkids.com/teachers/lessonplans/pdfs/grieg/Grieg%20Lesson%20Plans%203-5.pdf (lesson plan and materials for grades 3-5)
2. "Danse Macabre" by Camille Saint-Seans. This is really kind of a creepy song, so I really only use it for upper grades.
Youtube link to creepy 1980s cartoon: http://www.youtube.com/watch?v=9CHqhsMP80E
Here are the slides to a PowerPoint presentation you can use (I don't know who made this to give them credit, but it is very well done. Good job, whoever!)