Hi. We are planning to go on a very long road trip in an RV from Phoenix then drop off my sister's kids in Las Vegas then enroute to Vancouver & definitely passing by Seattle. Can anyone suggest best route. We have to be in Vancouver b4 July 30 and first time for us to travel in a 42ft RV so any advices on best routes/ rv parkings / must-see places.. We do want to go 2 other places on our way back to Phoenix. Thanks in advance for your advices.