According to my Autumn Spice and Everything Nice poll, cinnamon--by practically a 6-1 margin--is the most popular fall flavor.
Voting still remains open, so feel free to weigh in.
Thanks to all who already voted and to those who commented. Jem got me thinking about cardamom (and the cardamom and rosewater cookie I was thinking about doing last spring), and Alicia reminded me how well black pepper works in spice cookies and cakes.
I don't know about you, but I think an "Autumn Spice and Everything Nice" cookie is in order.