Use wear denim every day on my bike, and up untill about feb 2011 I wore holes through my pants at the rate of 3 pairs a year. They were always "vintage" / stone wash style.
In feb 2011 I purchased 2 pairs of cheap plain denim (un-stone washed) jeans from GAP and fortunately no holes since then. I'd even say I'll get another year out of them.