Lincoln Creek, up Independence Pass from Aspen has a lot of goats. I've hiked up Grizzly Creek to Grizzly Lake many times over the past 20 years and have seen goats probably every time. The trailhead is at Grizzly Reservoir. On the other (west) side of the valley I've seen goats frequently on Truro Peak while fishing Truro and Jack lakes. Lincoln Creek sees a fair amount of traffic due to proximity to Aspen.
There a lot of goats and spectacular country in unit 13.