Check WSDOT before taking WA530. That's the road that was closed by the Oso landslide. They got it cleared earlier this summer, but now they are closing it intermittently to raise it above future flood waters.
But speaking of 530, it does lead to the Mountain Loop Hwy. This gives access to one of the highest concentrations of hikes in the Cascades. Granite Falls to Barlow Pass is paved, and includes an easy hike to perennial ice at the Big 4 Ice Caves. The eastern segment running north from Barlow Pass is gravel, but well used by locals seeking 'dispersed camping'. Darrington north to WA20 is, at times, a virtual tunnel under big leaf maple trees.
Near the junction of 530 and 20 is Rockport State Park, a beautiful patch of old growth forest. So old, in fact, that they had to close the camping section for fear of falling limbs. But it is still a nice lunch stop, and forested hiking.
And nearby Sauk Mtn is a good place to stretch your mountain climbing legs (leave the trailer below at Rockport).
