I know someone who lives in Yellowknife, and it's the only place in the Northwest Territories that even remotely looks like a city, and it's a city along one or two streets for several blocks, a number of suburbs sprawled out around, and that's it. Summer is still pretty mild there so it's not like you're wearing thick jackets in July.

I've visited Whitehorse in the summer, it was nice, I really loved the 2 hour sunsets, it was like time stopped while I took in the river. I bet both places are much different in the winter.

Because of long days in the summer, every bedroom has blackout curtains to fully block the sun. Many people work or study seasonally then fly to Edmonton, Vancouver or Calgary in the winter or travel back and forth. Air North is expensive-ish but is the best service I have received from a domestic airline.

Stuff is a bit more expensive there. Nobody follows the speed limit because outside the city there's like one mountie (police) for 100s of km.

Didn't live there but looked into moving there (to Whitehorse), so this is only from personal research and talking to recruiter;
Beautiful nature to enjoy.
Relatively cheaper housing (if your job pays enough).
Smaller communities (good or bad depending on your preference).
Somewhat limited choice/somewhat expesive general cost of living (groceries/household stuff etc and not easy shipping).
Higher likelihood of depression/burnout, though some decent employers "try" to offset it with few extra vacation days or even, IIRC, like 1 continental flight (including Carribean?) covered for vacation. Don't remember whether that flight thing included partner or not or if it was a specific thing for Whitehorse/Yukon as a whole.

Edit... completely forgot, wildfires can be a real fucking problem, not just a thing you see in the news (speaking as a metro Van person)

Very quiet, I lived in Whitehorse for a total of six months and it's really like just being in a small town. The nature is beautiful, the people are crazy and nothing is ever crowded. lol Things are very expensive, food, building, bills. You name it. Cellular and Internet and power are all quite unstable, Whitehorse currently has higher power draw than their own production and they've been trying to fix it for the last few years. Some cellular towers seem to have barely working links so you can find that you have connection but can't load anything.

Overall I'd say at least for specifically Whitehorse it is the perfect place to live if you have money and love nature. Just don't expect to be doing any fun events unless you're the one who made them. XD