Seattle is USDA zone 8 and even 8b or 9 in areas close to water. Sourwoods do great in this area. I have had one in a large container for several years that I am still trying to figure out where to plant permanently and there is a very mature and stunning specimen on 125th street in north Seattle just west of the freeway. A very nice smaller tree with interesting flowering and dynamite fall color.

Among my very favorite trees. Be aware that these are quite slow growing (which can translate into expensive when you go to buy one). Also, they resent disturbance of the root zone. As g-gal mentioned, these are one of the most reliable & dramatic trees for fall color, and, in fact, are beautiful year-round. There are some nice old specimens in the Washington Park Aboretum, which prove that these will become quite large, but only after many years.
Plant one...or two - you won't regret it!

One of the Arboretum specimens was 48' high in 1989. Another, in Tacoma, had a trunk 4' 1" around and an average crown spread of 25' the following year. See Van Pelt, CHAMPION TREES OF WASHINGTON STATE.

Here is a link that might be useful: Trees of Seattle

Thanks, all !! ... and to gardengal48: I spotted that tree on 125th and guessed that was what it was but hadn't stopped to talk to the owners.

Paul in Shoreline

I recently purchased saplings (18-24in.) from a mail order company,that came bare root. Can anyone recommend a source that they have used? I am trying to find a larger older tree. Thanks Joel in Ohio

joel_beeman did you ever find a place? I am looking for the same.