Here's six reasons (stolen from bicycling.com) that make fall riding great!
#1 Riding thought the leaf fall!
#2 Finally getting to pull the warm riding gear out of the closet!
#3 Not being a sweaty mess when you finish a ride!
#4 It's Cyclocross Season!
#5 Biking around Apple hill for cider, beer, and fall festivities!
#6 Pumpkin / Oktoberfest Beer!