But I understand why you don't want to trash your expensive pants. The Guides go for, well, I'm not certain. Do you really mean Mountain Hardwear? Patagonia makes a Guide pant ($169) and so does L.L. Bean ($125). But not Mountain Hardwear. In any event, they're certainly repairable. A company like Rainy Pass Repair in Seattle (www.rainypass.com) could sew an abrasion-resistant butt patch onto the pants, allowing you to make an exceptionally cool fashion statement and also avoid glissade bottom. Alternatively, you put up with an extra pound and pack some overpants for glissading, something like the Dutch Harbor Rain Pants-just $40, and completely waterproof.
And there's one other alternative, which I'll make gently: Revise your glissade technique. Sitting glissades seem easy and intuitive, but they're difficult to control. It's too easy to start tumbling, then whack into rocks or a tree. Happens all too often. Better to use the standing technique, where you can hold your ice axe in the ready self-arrest position. And it's pretty effective-often you can execute a standing glissade more readily than sitting one
That said, some years back I climbed the Kautz Glacier route on Rainier. Long ascent over steep snow to camp at 11,000 feet. Wow, what a descent THAT was. Sitting glissade for some 4,000 vertical feet. Man, that was fun.
Oh, and one more thing: Of course I've saved you money!!