From S. California, come up on the back side of the Sierra, through Donner Pass to Winnemucca NV (good stop, with barbecue), then east until you can come up the EAST side of the central mountains of Oregon, through the TriCities to Spokane. We did this to San Diego with a stay in Winnemucca and a real long drive to San Diego, back via San Francisco: we found the back highway down the Sierras, part of the way in Nevada, a less congested route, but this may vary seasonally.

From Dallas—take the route to Amarillo, then to Clayton, then to Raton. Good stop at the Motel 6, then take I-25 north to Buffalo WY, Motel 6; then on to Spokane.

From OKC or Tulsa: head out I-40 to Raton and then the same {Buffalo, then Spokane) , or up to Wichita, then Limon CO, then overnight in Billings, if you like that route better…never done that one but once.

From anywhere in WA west: I-5 to I-90. I-90 runs through Spokane.

From anywhere in Oregon eastside: go up to the TriCities, then to Ritzville, then Spokane via I-90. On the west, you’ve got a choice at Portland: go up I-5 and take the White’s Pass route; or through Seattle to I-90; OR take the scenic route along the Columbia River past Multnomah Falls and cross at the TriCities, then to Ritzville, etc.

St. Louis: get up to I-80, then take it to Cheyenne WY, up to Billings MT then west on I-90.

If you are on this list, you can do it in 2 nights on the road. If you are farther, and traveling solo, it would be cheaper to fly.