Timing is everything. "Spring" = ?

The Pacific NW is gorgeous in the late spring; it can be dreary and rainy in the early spring.

Probably I'd suggest one of two alternatives. First, you could head up the coast north from San Francisco through the coastal Redwoods to the Oregon coast. The trees in and around Redwood National Park are stunning - really a unique environment which has left my visiting British friends universally gobsmacked; plus the misty/drippy climate in the spring is magic for photography. The Oregon coast, in particular the southern half, is wild and rocky/stormy then, too, so prime stuff for shutterbugs.

If you want to do the whole deal, California > Seattle/Vancouver, it's around 24 hours' drive time from LA using the inland route (Interstate 5) and around 40 hours hugging the coast, so do the math and see if you've time. You could hop a quick flight from LA to Seattle, pick up a car, do a big loop - Vancouver, Seattle, Oregon coast, Redwoods, back to Seattle via Portland - quite easily with a couple of weeks.

OR, for something entirely different, go out to Palm Springs for serious mid-century cool, then hit Joshua Tree National Park. Then shoot past Vegas and head to Bryce Canyon and Zion National Parks in Utah, just a few hours up I-15 past LV. Again, depending on the timing, you can still have some snow on the higher elevations (both parks are quite high) with amazing contrasts against the red rocks.