Most of the problems being discussed here in this thread regarding work hours per week, commute times, finding time for leisure and exercise and family time, the time spent dropping off kids at school, etc -- there are mostly unique to America. Americans could really learn a lot about how successful you can be despite spending less time at work, as well as less time fretting about other things, by looking at any of many countries on the continent of Europe, who offer a much better work/life balance but with no sacrifice on work output.
Some of the most talented and productive developers I know are in the Netherlands, France and Germany, and have a lifestyle that would be considered impossible by many in the States.
The brain needs time to recharge, time away from "work", time to think about work without actually doing work, and the punch that gets packed into a shorter work day can be much greater if the brain is working at optimum capacity, which usually doesn't happen if it is taxed for loads of hours day after day after day.
For me personally, my best ideas come when I am away from a computer, and my brain is free to wander. The more time I sit at a computer, ironically the less likely good ideas will come. Most work environments in the States have not learned this yet.