Eastern Washington is very different than the west. And hotter. You'll see that change before your very eyes as you drive East from Portland. Depending on what part of Texas you're in, the area you're going to may look very much like home.
The drive through the Columbia Gorge is a really pretty one. If you can take the time on your way to stop at some of the scenic viewpoints, do. Multnomah Falls & Historic Columbia River Highway
I love Washington. My Aunt lives in Seattle. My Ex In Laws live in Spokane. We used to go up the California coastline into Seattle then over to Spokane. Long way to get there I know but oh so pretty. I went to a dog show in Yakima one time too,very pretty state.