For work, play, and longevity.
These pants are the ultimate in style and function. I have a hard time wearing any other pants to tell you the truth. They are incredibly durable without being too heavy, but I would not recommend going on a major backpacking trip (as Evan noted) with them because they will take up quite a bit of space in a bag, weight or not. If you want a pair of pants that will take a beating and last forever, these are those very pants.