Snoqualmie is great for anyone who is living in Seattle and needs to ride. As a vacation however, the hill is less than ideal. Mostly I say this because of the crowds, especially those that manifest on weekends. It's the closest resort to downtown Seattle, and that means a lot of people coming up the interstate, and then piling on to the slopes. You'll spend a lot of time waiting in line.
The other problem with this place is snowfall. It's base is at the lowest pass over the cascades save for the Columbia River. At roughly 3,000 feet, the bottom of this place gets frequent rain and or very, very heavy wet snow that, especially during storms, makes skiing very difficult. Alpental is a good escape, given that its summit is over 5,000 feet, and snow up there generally remains pretty consistent. Alpental also has very challenging terrain and great sidecountry access as well.
The other big bonus that you get with Snoqualmie is night skiing, which makes the ticket more of a bargain if you plan on spending more than seven hours on the slopes.