After seeing the original post (which was posted in 2004), I thought that we should see who would win for the hardest-working aircraft in 2008. In 2 weeks or so we should count the votes and see what plane won. So, to start things off, my vote goes to...
Boeing 757. It has been going strong for 26 years, and it is so versatile. In 2008 it was doing short-domestic hops, coast to coast flights and flying across the pond. It is a very well designed aircraft for all kinds of flying.
Other runner ups include DC-10, 747 classic, and 727 freighters. They fly tons of hours and cycles and we rely on them for overnight shipping. Finally, the DC-9. Northwest has kept them going for over 40 years, and they work hard still.
So what's your opinion?