I live 4km from the loading dock (location of indoor bike cage) at my work place which is really too short a ride for any form of health benefit. My wife leaves for work either at 7:15 or 5:45 (for her 7:30 or 6am shifts) so I'm up early with her. (Oh yeah, the dog wants out to pee at about 6 and the cats start whining for food at the same time.) I'm the type of person who gets ancy when I'm ready to go but have to wait so I might as well use the time to bike. In the winter, I'll take a shortish route, just shy of 7km, to avoid hills (they're all short distance, steepish hills but I don't want to either stuggle/slip and slide going up or get too much uncontrolled speed going down in snowy/icy conditions). In the summer, I use commuting for fitness, enjoyment on the bike and training for either touring or organized bike rides so I'll flip between routes, depending on my level of fitness and needs, that are 20, 22, 33, 42, 55 and 66km (I've only done the 55km one once because I need to be on the bike at or before 6am in order to make it to work in time for a short shower, no time for a shave and the 60km one was done on an extended ride home). This fall, I got a bit lazy and was riding either the 9 or 10km route, they have the advantage of allowing me to leave later than I need to for my regular 20km ride and therefore, less of the ride in darkness. I have found another route (actually an extension I can add to the end of any route) of about 8.2km which adds 81m/265ft of additional climbing (which includes "suicide hill", 12% grade according to RideWithGPS.com).