Big White
The most complete family resort in Canada, genuinely ski in ski out and built for children.
Big White tops the list because almost every bed is true ski in ski out and the whole resort is geared to families. The terrain is forgiving, the snow is light and reliable, and the village runs tubing, skating, sleigh rides and a kids center so nobody is bored off the snow.
It edges out Sun Peaks on sheer convenience, since you rarely need a car or a bus all week. The trade off is that it sits a few hours from Kelowna airport and the village is functional rather than charming, but for a stress free family week it is the clear Canadian benchmark.