Do what she wants to do.  Get her a lesson (early season they have good deals a lot that include lesson, rental, lift for cheep so you dont need to drop a ton of cash).  I would suggest snowboarding because the first hour of snowboarding sucks, but by the end of the day you pretty much have it down if she has a good instructor.  Skiing can take several lessons, posibally years to have it down unless she is really talented.  Good luck, I am 0 - 5 in this department, make sure she is stoked to go, if not you are wasting a good day of skiing.   If you  are old enough to drink, the bar at the resort is always a solid backup to prevent a complete waste of a day.