I spent most of my high school career night skiing. At the time I loved it. You either only ski weekends, or you go night skiing and still get 5+ days a week on the hill. Overall though I'd say night skiing (as far as the park goes) sucks ass. Shit gets way too icy and it's harder to motivate yourself to progress.
That being said, a little night time powder with a couple beers is one of the most fun things you can do I'd say.
Overall though, gonna have to say skiing during the day overweighs the benefits of night skiing in the end.