I have a 15 mile commute, as soon as the snow melts I use the trip to and from work to train. I currently have a 36 mile route I use each way, it is mapped out for a variety of purposes. There is several hilly sections, and a couple long sections for intervals, lastly I try to keep as safe from traffic as possible. This is my sixth year using the commute as training time, so far the only downside is as I stretch the distance it takes more time from my day, (at work).

If you can avoid city traffic there is much to be said for using the commute for training time as well as enjoying the ride.