My current commute is from west metro Denver (down) to downtown and back. ~10 miles each way. It's all on the road, but the roads either have wide bike paths, are frontage roads, or just wide roads period with fairly low traffic. It's almost all hill or slope with about 700 feet of elevation change. Takes about 35 minutes going down and 45 up, loaded with my books and binders, food, extra clothes, repair kit, etc. etc. I have to cross 2 sets of light rail tracks and 2 sets of freight train tracks each way. I go through a wide variety of neighborhoods, from normal suburbia thru the country club and thru some areas that I would ride but not walk through at night. Tried riding on the elevated-highway-with-sidewalk to avoid the tracks once but apparently that where everyone puts their recycling. Some of that probably didn't sound too nice but it's beautiful every time. I'll take a bad commute on a bike over a good commute in the car.