This weekend I visited with family in Eastern Washington. During this trip I came to the following conclusions-

  1. The route should be East to West, starting at the Idaho border and ending at the Washington Coast. 
  2. Finding and carrying water is going to be a problem as we attempt to stay hydrated in the more arid parts of the state.
  3. The timeframe for the full ride will probably need to be late Spring or early Fall. Summer can be oppressively hot in Eastern WA.
  4. My Cyclocross tires (700x32) may not be wide enough for the terrain. Will need to do some test rides in the Eastern section to verify. 

During the return trip to the Seattle area we drove up near where the John Wayne Pioneer Trail crosses the Columbia River. I found the railroad trestle but didn't realize that the trestle was actually the trail until we were well past it. We will have to do this route again next month and look at the trail crossing.