Knowing that you need full hook ups.
Spokane to Leavenworth with a stop at Grand Coullee will be a full day, there are two full service camp ground in Leavenworth, Icicle Camp Is our Favorite.
Day 2. Back to 97 north and the north Cascade highway across to Concrete is another day, there are two very nice full service camps just east of Concrete one is KOA the other is private. That's a full days drive.
Day three will be getting to the Olympic Penn. via Highway 20, be certain to have reservations for any ferry you plan on taking. (specially the Key Stone to Port Townsend ) its a smaller ferry and is usually full. If you miss it. there is a very nice camp At Ft.Casey, right next door to the ferry.
The last real town with all the big stores is Oak Harbor, stock up before you cross to Port Townsend. the prices double west of the sound.
OBTW the north end of Whidbey Island has North Whidbey RV park. across the highway from Deception State park (which has no hookups)
