I'm not sure it would be worth the drive. Its an awesome mountain, if you hit the right day, but thats tricky. Great if you have a seasons pass. But as Grant said, if Alpental's shitty, you can go across the freeway (like a 2 minute drive if that) to West or Central which both have great parks (and your ticket for the day is good at all the areas).
But don't be fooled by any literature or websites... all of snoqualmie is small, its not really a mountain. Alpental is ok size-ish, especially with the back country. But compared to "real" resorts (like Whistler, etc) its nothing. I still love it though, and its my home mountain.