It was good to meet you at the Native Fish Society dinner!
I have just become a member of the FFCO and while I was exploring the site I came across your message. I fished that area about 10 years ago so possibly my info will be out of date. I fished in February (a backcountry ski trip gone bad) and found really exceptional fish in the Roaring Fork which is the larger stream coming out of the Aspen area. The Frying Pan is the most famous and at that time of year (run-off) it might be best because it is a tailwater stream so the water might be in shape. In the winter, the fishing was really good on the Roaring Fork AND in the main Colorado that flows through Glenwood Springs and is where the Roaring Fork enters the Colorado. The water conditions might be poor on the main Colorado and the Roaring Fork. I remember a great fly shop in Carbondale (heading towards Aspen from Glenwood Springs). If you have never been, I recommend the public hotsprings at Glenwood Springs followed by beer and burgers!