My route is from Brooklyn Center to downtown St. Paul, 1/3 on bike trails, 2/3 on roads. I ride every day rain or shine for 8 months of the year (winter is too great a challenge).
I race triathlons so bike commuting gets my biking in, I then run and swim on my lunch hour (my wife and 3 kids hardly know I train even though I put in 3 hours per day).
I have had 9 different work-to-home locations over the last 18 years (from 9 to 18 miles one-way) and have always found a way to bike, with the exception of one year where I drove because I worked only 1.5 miles away (it was too close to bother with biking).
It takes me on average 55 minutes to ride 18 miles to work, driving takes 45 minutes and the bus takes 85 minutes. Biking is fun, cheap and pollution free; it's a shame more people are not aware of its benefits. I have written an article about it that will soon be published at www.thegreenguide.org - check it out.