hardiness will depend to some degree on provenance/seed source---forms from high elevations ( roughly 4000' in the siskiyou mtns of southern oregon/northern california. for example might be hardier than lowland populations). you can try contacting Ian at the "desert northwest nursery" and see if he has any collections from eastern washington (?) available. that said, even the hardy forms will very likely prefer a planting site sheltered from cold dry winds, with excellent drainage and likely mulched with gravel to conserve moisture and keep the soil cool during the summer. these plants while definitely beautiful and majestic are not especially easy to grow even in their native habitat so good luck. BTW, a reasonable rule of thumb is how many other evergreen broadleaf trees grow to large/mature sizes in your area and are generally unhurt except in the worst winters---if you have several evergreen tree species (excluding conifers) growing well in your area your changes in growing this plant will likely be better.

Don't rule out Arbutus texensis. Having seen both A. menziesii and A. texensis in habitat, I'd say the Texas madrone can be just as pretty, it's just smaller. In fact if I could have only one in a garden, I'd take a A. texensis/xalapensis with particularly red bark: there was some variation. Pictures I've seen of A. arizonica don't look as ornamental. Ideally someone would get permission to take cuttings of a selected, hardy A. texensis in a protected area, but that will never happen. I'm not even sure if they are easy from cuttings like the European Arburtus or if they would need grafting like Kalmias.

I saw Arbutus texensis in west Texas that looked 100% fine after that area's big freeze in 2011. At the elevations where I was hiking, it definitely got down to 0F. Unfortunately the handful that have been in commerce were collected from lone arboretum specimens collected from milder areas, which is doubly problematic: they may not be as hardy and they might be inbred.