Silver Mountain is super easy to get to from I-90 (so is Lookout). There is a gondola that goes straight from I-90 to the top of the mountain.
I haven't skied there in 6 years or so (used to live near Spokane), but I remember some pretty nice mixed terrain, especially the very steep glades off the top, and some long bump runs. Also there is a nice little corniced/bowl area accesible by a short hike of 5-10 minutes (Warner Peak?).
I have not been to MSB but Silver is a good choice for a quick hit and they are having a banner snow year as well. Kellog is an old mining town and now a Superfund site (I believe). The bottom of the mountain is very desolate from all the lead/siver smeltering in the past, but the top has great views of the Bitteroots etc. Kellog used to be very cheap for lodging etc. Silver gets a lot of day traffic from Spokane/Coerdelane on the weekends
It used to be called Silverhorn and before that Jackass (what a name) before the gondola days.