Ron et al.,
I would have to agree on the feather ID of red-tailed hawk. As a part of my job I routine have to look at feather spots of raptors and other birds and have examined red-tailed hawks, great-horned owls and other raptors. I've never seen a great gray owl feather spot, but your feathers appear in the photos to match my experience with red-tailed hawk (and match the photos of red-tail in the USFWS website below).
For questions on raptor feather spots there is a great website the the USFWS put out and has feathers of most of north american raptors and has both red-tailed hawk and great-gray owl on there (usually primaries and remiges).

http://www.lab.fws.gov/featheratlas/index.php

I think your first encounter with the wonderful great-gray is still to come, hopefully in the form of a live bird!

Scott Downes
downess at charter.net
Yakima WA