Yukon: See
Many of the visitors in the winter come to the North specifically to see the Northern Lights. In the summer, the days are very long (up to 24 hours when north of the Arctic Circle). If you can't see them outside, see them inside at the Northern Lights Centre in Watson Lake, which features a northern lights multimedia presentation in a theatre.
Dawson City is the place to go to get a taste of the history of the Gold Rush. The "Dawson Historical Complex" is a National Historic Site encompassing the historic core of the town. Diamond Tooth Gertie's Gambling Hall is a touristy relic with can-can shows and gambling. The Paddle Boat Graveyard has a collection of old paddle boats that you can crawl around in and on.
In Whitehorse, you'll find sternwheeler paddleboat, turned into a museum, the MacBride Museum of local history, and the Beringia Interpretive Centre about the land bridge from Asia to North America. The Tage Cho Hudan Interpretive Centre in Carmacks and the Da Kų Culture Centre in Haibes Junction showcase the past and present culture of the territory's First Nations.
The Signpost Forest, at the intersection of the Alaska and Robert Campbell Highways, in Watson Lake has over 80,000 signs to cities and towns around the world.
Seeing the caribou migration near Old Crow is not an easy thing to do, but would be an amazing experience.