Help with Sept/Oct trip Seattle to Phoenix

We are getting ready to depart on our adventure in a Cruise America motorhome from Seattle to Phoenix. Any last words of advice for routes, attractions, parks, etc? Right now, thinking of going towards Leavenworth, then down through Yakima and on to Bend, Or, then maybe over to Lakeview or Klamath Falls. Which route would be better? After that, thinking about northern CA then western NV, Lake Tahoe, Las Vegas, Lake Havasu, and Quartzite before heading east to Phoenix. Your thoughts?

Thanks in advance,

Kathy