While you have a point of sorts, changing from a 24 hour day wouldn't help, there's no way to actually create more time. If days were twice as long then we might get more done "in a day", but we'd also live for half as long as we do currently, it would just balance out.
Personally I have DSPS (http://en.wikipedia.org/wiki/Delayed_sleep_phase_syndrome) which does make the typical structure of a 24 hour day a real pain for me.
Right now I'm working in a job that requires me to be actively working at 9am, yet I'm at my most active/awake state late at night. Luckily I do most of my work at home, travelling up to the office once every couple of weeks at most, so as long as I'm available during 9-5 hours, I'm still fine to leave the work that needs me at my most productive for the evening, and the work is pretty flexible in terms of when I want to take a few hours or even a few days off.
I changed my role slightly at the start of the year so 2010 I've been mostly working from home or in the office, but for the two years before that I would be travelling to events, some in the UK, some in Asia and most in Europe, very regularly (I think I worked it out that in 2009 I spent ~35% of the year's days outside the country). That was a real pain, because when you're away working you can't create your own schedule. Luckily sleeping pills were helpful (I ended up taking them every other night when away, which left me able to drink plenty on the other nights, as alcohol+sleeping pills don't mix well).
DSPS isn't exactly a reply to your question, it just exacerbates the problem for me. I do also find I don't have enough time to do nearly as much as I'd like to, the things that I think get left behind the most (compared to how much time I'd like to spend on them) are exercise, reading novels and coding.