In reply to SFrancis:
Some sort of mid to lightweight softshell trousers I reckon. I've got a 15 year old pair of Patagonia that still work fine and some 10 year old decathlon ones that are also great. I've found short of sticking a crampon through them (and through my calf muscle also one time!) I don't get holes in them. They've done thousands of pitches and loads of hiking and skiing - so good value in the long run. If you've got a Decathlon nearby don't just look in the climbing aisle (where the clothing is all Simond now I think) look in the trekking aisle at the Quechua labled ones - they do some really nice ones of different styles and weights with the normal good prices. I recently accepted my middle-ageddom and bought a pair of Quechua zip off trekking trousers and they are good even if they look, well like you can zip off the bottom of your trousers which remains slightly silly.
For the last couple of years I've been using the Wild Country Torque pants a lot that I reviewed here:
https://www.ukclimbing.com/gear/review.php?id=7603 I still really like them (except the colour but I'm reconciled to that now), particularly for rock climbing in the colder months up on the moors. Basically they work as well more "technical" looking softshells, but look more normal if you go to the pub after - this years version in khaki look great, almost tempted to get a second pair in that colour.
http://www.wildcountry.com/en/mens-torque-pant-2/