My commute was 14 miles each way when I lived in DC, and it was terrific. I had so much more energy on my commuting days. It took me 1 hour and 10 minutes, with a slight decline in the morning and a slight incline in the afternoon. In the winter, I would mix it up with the Metro because of the darkness since I don't ride in the dark.

Now I work from home, so my commute is history. I miss my commute, though, and do most of my errands by bike.