Originally Posted by Robert / Seattle
With that white median breast and belly, bordered by the darker "vest", I'd say you have a fine example of an Olive-sided Flycatcher. A common summer resident here in Western Washington.
I think in this case you are right but Western Wood-Pewees can have almost as dark vest with the white belly. I think since the bill appears to quite thick, the head is pretty dark, and head shape looks good as well it probably is Olive-sided.