Seattle, WA to San Antonio, TX in April - route suggestions?

This is such wonderful feedback and advice! Thank you everyone. We won't travel the i5, if we can possibly avoid it. I've driven it in a car and find the idea of doing it in a 40' Class A with toad isn't the most appealing. The i90/i84/i15 and on looks the best for us so that's our tentative route, depending on weather as the time approaches.

Thanks for all your help, it's much appreciated.