Responding to a camera search thread, Rick Dreher mentioned the ClearViewer as a possible solution to my desire for an optical viewfinder, which is becoming an endangered feature in the compact camera world.
So I ordered one that mounts to the tripod socket for my Sony W170, and it has potential. It places a 3 diopter lens about 1.5 inches (4 cm) from the LCD screen and allows you to view the screen in good detail. There is significant 'pincushion' on all four sides, but for this application that does not matter. I can see all four corners easily, plus any shooting information I display on the screen. I'm nearsighted, so don't need to wear my glasses to do this.
More significantly, with my head this close to the camera, the LCD screen is Very readable, even with the sun directly behind me. In the worst case scenario, with the sun to my left glare can sneak in from the side, but it is easy to block by bringing my left hand up to shadow the screen as the space between my face and the camera is less than 2 inches (5 cm).
By flipping the lens over the viewer folds to the LCD screen for stowage, adding less than 0.5 inches (1 cm) to the depth of the camera.
If this elegant kludge works well enough, it opens the door to many compacts (e.g. Canon S90) that lack an optical viewfinder.
Additional details can be found at ClearViewer. Gary Robertshaw at Clearviewer had not made one of these for my camera but was ready and willing to do so. It took 10 days from payment to delivery. He was a pleasure to work with.
I'll post again after a bit of time in the field.