i did that at least once a week in the summer and i always got really into it and felt like i was master chief.
but, back on subject.
Definately do it!
do either one, but make sure you do enough to trip balls to the wall.
ive done shrooms a few times skiing, and when there is shitty snow, sun shining and its not too cold its one of the best experiences you can have.  the trick is to only ski when you really feel like it, although i do recomend at least one ride on the chairlift when your peaking, if you arent afraid of heights.  theres a stoner hut in the woods thats easy to get to at mt baker and much of the time i just tripped there. wandering around in the woods when its snowy is fucking great. plus going skiing is a great excuse for having 8 hours of free time.
i consider the mountains in the winter to be the height of beauty in nature and frying in a beautiful place makes it intensely spiritual.