Your descriptions still sound like Northern Oriole nests to me, Grant.
Their nests persist very well from year to year, and they can be pretty
common in a grove of trees. I should think they would be fairly common
where you live, and they are definitely riparian in habitat, whereas I
think of Bushtits as nesting in denser forested situations and with their
nests more hidden. Kinglets wouldn't nest in such a situation. Are these
nests whitish or pale gray? I think that would confirm them as oriole
nests. Maybe you can look at them through binoculars and post as good a
description as possible.

Dennis Paulson phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416