I have a few pairs of Columbia Sportwear cargo pants for hot weather climates. They are synthetic, light but tough. They were what I predominantly wore while in Baghdad.

For cold weather climates, I have a couple pairs of synthetic waterproof breathable rainsuits (coat and pants) from Walls for the wet times, and for the really nasty stuff I have some composite over pants that are waterproof, breathable, but well insulated. I also have a pair of waterproof fleece pants from Rivers West, which I've worn in the coldest environments in comfort.

I try to avoid cotton in survival clothing because I've found it to be inferior for both hot and cold environments. It is great for casual wear, but useless when wet, whether hot or cold, unless it is treated so as to make it waterproof.

Woolies aren't bad for hiking. I like the old swedish army wool pants, except my wife hasn't figured out yet that wool has to be washed in cold water and dried without excessive heat.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)