The capital city of the Yukon Territory (since 1953, to the continuing regret of much smaller and isolated Dawson City), Whitehorse will likely have a prominent role in your journey. The territory's two great highways, the Alaska and the Klondike, cross here; it's a hub for transportation (it was a terminus for the White Pass & Yukon Route railway from Skagway in the early 1900s, and during WWII was a major center for work on the Alaska Hwy). You'll find all manner of outfitters and services for explorations across the territory.
Not immediately appealing, Whitehorse rewards the curious. It has a well-funded arts community (with an especially vibrant visual arts community), good restaurants and a range of motels. Exploring the sights within earshot of the rushing Yukon River can easily take a day or more. Look past the bland commercial buildings and you'll see many heritage ones awaiting discovery.