We like WA 20, better viewing. Road has lots of curves especially around Ross Lake on the western end in the North Cascades NP. Just take your time and enjoy the views. This highway has less traffic than US 2 and you won't have to mess with the urban stuff around Everett and Wenatchee. But if you do take US 2, stay at the state park near Orondo on the Columbia River. There's good camping in the North Cascades NP near Newhalem and near Ross Lake. Another nice place is Bridgeport SP, a little south of WA 20 at Rufus Woods Lake on Chief Joseph Dam. More camping near Newport, Colville, Republic, and other towns along the way. A suggestion might be to take US 2 westward from Spokane and then when you get to Wenatchee, turn northward on US 97 and head to Brewster and Twisp where you will eventually tie in with WA 20. Suggest that you get on USFS web sites for more complete info or stop in one of their offices along the way.