I have never hunted in OR, but been through that area on several occasions. I have seen one quite nice muley on the breaks on the road between Joseph and halfway. I know there are a lot of elk in that area too, but it has been hit by wolves pretty hard and gets hunted pretty hard.
I have hunted a bit in Idaho in the snake river canyon and have noticed that the elk are down low pretty early, so if you are not seeing any on top, don't be afraid to go low, like maybe even over half way, which is deep (deepest canyon in North America). If you are over the edge, you will be in big muley country, so if you can afford a tag, it would be nice to have. The Idaho area I have hunted gets hit hard during the Rut by the natives on top, which may be the reason they head over the breaks.
Shouldn't be much different in OR except the hunters will be using different weapons, which the elk don't know the difference; they just head down hill.
Good Luck, thanks for the service