how "White should snow be.?

All answers to your question so far have merit. As far as a simple opinion goes, I would go down about 1/2 in exposure then play with curves and/or gamma to bring some detail to the snow without losing the overall brightness. I sometimes find that I need to tweak either the white balance, or hue/saturation to pull a blue cast from bright snow once it's no longer blown out (though sometimes that bluish "glacier" cast is desirable.)