Becky's GGG pants are great!
I use mine for most trips that do not require a cave suit. Berta has the bibed version that she really likes. Tough material, does not hold water, much warmer than nylon or cordura.
If you want something of a lighter weight than the GGG pants, check out Chilli Heads - Stretch Cordura Leggings.
Just let Susan know that you are a caver and she will reinforce the stitching. (for free!)
http://www.chilliheads.com/leggings/legcordura.htm
They are heaver than light weight poly-pro, near mid- weight. TOUGH as nails!! I’ve been wearing them for close to 8 years, without anything covering them and have yet tare a pair!
For my style of caving in TAG that ranges from horror to wet to dry, I am happy with the a Petzl cave suit, the GGG pants and Stretch Cordura Leggings.
These 3 items cover it all. (pun intended).