Thanks to two other bird-watchers, at 2pm yesterday (Friday) I saw a Snowy Owl on the house at 3210 73rd St, between 32nd and 33rd Avenues.
It was on the roof, a few inches north of the chimney. The best view was from standing west of the house on 73rd St.

A few locals told me the second Snowy Owl is still around. One person said it was atop the yellow house on the NW corner of 72nd and 34th St, although I wasn't able to find it.
Locals also said the owls may, from day to day, roost on different rooftops and/or in some of the taller trees in the neighborhood. So, if you don't find them on your own, ask the locals.

Joe Sweeney
Wedgwood
NE Seattle, WA
sweeneyfit at mac dot com