Fairbanks or Barrow
You are really not serious are you?
I am serious, everytime the race visits Alaska, its mainly around the Anchorage area. Fairbanks is a good sized city and Barrow is the most northernmost city in the US. Fairbanks has alot around there and Barrow is right next to the Arctic Ocean. Imagine teams taking a dip in the frozen sea as a task, they swam in a frozen lake in South Korea during Season 4. Plus Juneau the state capital is also on my list due to the mountainous backdrop and the nearby glaciers.
I doubt that TAR would visit Fairbanks or Barrow during a season showing in the winter/spring period because it's just too cold. From the weather underground, I found this weather data:Fairbanks
November 25th (a random date a month from now that I picked)
Average High Temp 7F Record High Temp 54F
Average Low Temp -11F Record Low Temp -43
June 4th (a date that would have occurred near the end of the running of the current season)
Average High Temp 68F Record High Temp 86F
Average Low Temp 45F Record Low Temp 29FBarrow
Average High Temp -5F Record High Temp 30F
Average Low Temp -10F Record Low Temp -36F
Average High Temp 35F Record High Temp 47F
Average Low Temp 27F Record Low Temp 8F
If they visited either place in late November or December, they would be running around in zero or sub zero temperatures trying to accomplish tasks. Possibly as cold as 20 below zero. They would have to limit outdoor time greatly to avoid frostbite. Not to mention that poor Phil would likely be out there for hours unless it was an indoor pit stop. Polar bear plunge dips in the ocean would be very unwise. At the very least, you'd have teams shivering and complaining about how cold they were. That's not great TV. Also, camera and sound equipment might have issues being used in that kind of cold. I know that Fairbanks is prone to ice fog in the winter. That could impact air travel. Day time is down to about 5 hours and 15 minutes in Fairbanks and even less in Barrow.
If they ever go to either place, it would have to be in early summer for the seasons that start airing in September. Juneau is a slight possibility for November/December, but it also is subject to weather problems impacting air travel. They get some strong storms.