For pants, I bought a pair of Stoic softshells last year when Backcountry.com launched the line and sold them cheaply on steepandcheap.com. Really love them, and even in the damp cold Adirondacks had no problems, and needed no other layer besides the pants.
As for traction, I can't say much about Colorado, but for me I have a pair of MSR Lightning Ascents...I like the additional grip they give, and personally HATE the sound the plastic MSR's make on hard-pack....drives me out of my head! YMMV. I also have a pair of MicroSpikes for really hard pack days, and a pair of Grivel G10's for ice. In general I'll only have two out of the three on any given day...I suppose I might take all three on a >3 day backpacking trip since weather changes so much. Again, keep in mind this works for me here in the Northeast, so I don't know if the same applies out there.
There are a few other things I always have in my winter pack....my Patagonia down sweater, a pair of ski goggles and face mask, several pairs of gloves and socks, and an extra base layer (because I generally sweat on the ascent, and change at the summit so I don't freeze coming down).
Hope this helps - let me know if I can offer any other insight.