I have numerous versions.
The 3 main ones are:
1) The rare I want to ride home but not to work because it is freaking cold: .5 mile bike 30 miles bus \ light rail. I rode this one this morning.
2) The standard winter commute length (I have 2 versions of this one): 14-15 miles each way.
3) Summer full length commute: 56 miles RT.

Due to the fact that I would rather ride on the weekend and with a group of friends on Tues and Thursday #3 is not going to be the primary commute next summer unlike last summer. Probably #2.
Also, I work from home two days a week. Consequently, the largest # of days I ride to work is 3.