On the second day of my visit my nephew took us to Snowmass. It is by far the biggest of the 4 Aspen skiing Co. areas and is heavily patronized by families. On this basis he reasoned that it might have the easiest to find powder in the trees on the 4th day after a storm. Always take the local's advice. We found it in the Campground area on the periphery of the trail map. You had to go in pretty deep and it was pretty tight, after all it was 4 days after the last snow. It was also some of the best powder I have skied in a while and totally untracked. At the end of the day we took a run on The Big Burn, perhaps Snowmass' signature trail, in memory of my friend John, who succumbed to cancer several years ago. Perhaps his favorite thing to do in the world was to ski with his kids and grandkids on the Big Burn.
http://www.aspensnowmass.com/images/dyn/trailmaps/jpg-High/sn.html