From Spokane to "the West" you have three main routes; Interstate 90, Hwy 2, or the southern route, Hwy 395 to Pasco and then along the Columbia to the Pacific. They are very different drives.
90 is the fastest way, and it's 8 1/2 hours minimum, but can be done in a day. There's stuff to do along the way, but mostly it's used just to get from one side of the State to the other.
Hwy 2 is very different. It's mostly 2 lanes, cutting across the scablands to Grand Coulee Dam, the foothills up into Leavenworth, and the scenic drive through the Cascades. This is a 2-3 day trip (because you'll want to stop along the way).
If you're thinking of Vancouver, BC, you'll want to take one of those routes. But if you're thinking Vancouver, WA, and the Pacific Coast, you want to go down the gorge. The route to Pasco also cuts along the scablands (interesting geology story). Once it gets down to Pasco/Kennewick (Major Wine Country) you can follow the Columbia all the way to the ocean, another scenic drive with waterfalls.
I wouldn't worry about visiting any of the cities (I go to them all with frequency),