Growing up in Colorado, I have had the opportunity to check out a lot of the cities and towns in the State. One of my favorites is Breckenridge, in Summit County Colorado. Summit County is known for the sheer number of ski resorts it hosts, among them Vail and Copper Mountain. Breckenridge has the ski resort vibe going on, but it is also a great town with a lot of great things to do.
Like Aspen and Telluride, Breckenridge began as a mining town. When the mines stopped producing, the range of peaks to the south became the economic anchor of the town. Due to the large number of mines, the valley floor that Breckenridge sits in used to be covered in huge piles of stone, the result of dredging in the mines. The town has spent years reclaiming the valley floor, and from what I remember growing up, the progress has been amazing.
The Blue River winds through town, and has been the focal point for a lot of the reclamation projects the town has undergone. Along the river winds a multi-use path that runs 16 miles up to Copper Mountain resort, and from there connects to another paved trail that runs to Vail. Great for running and biking. Breck is also surrounded by some great rides, among them Hoosier Pass, Vail Pass, and Loveland Pass, all of which climb to at least 10,000+ feet. And of course the town is host to some great skiing and snowboarding during the winter.