The odds of seeing the lights vary with the suns activity. They aren't seasonal, and can happen anytime during the day, you just can't see them when the sun is out.
Fairbanks is a great place to go see them. Drive up to Chena Hot Springs for a better experience.
Strange, when we lived in Kodiak we never saw them, but have seen them on many occasions in Sitka. Both about the same latitude.
In Fairbanks, I always recommend "Reflections" (the couples place) as a nice pub.
