The main mechanism of failure of my jeans is crotch rub. I have big thighs and the rubbing of the friction or walking very quickly reduces the denim to the consistency of tissue paper with failure following soon after. This is expensive and embarrassing.
I wonder if a pair of jeans such as prana's offerings with elasticity and a diamond crotch might be suitable for my everyday needs?
In reply to andic: I tend to have a similar problem; I find blue harbor M&S jeans last a long time as well as RI. However, in most cases I just buy cheap matalan jeans; they look decent and are cheap enough to not have to worry about their death within a few months.