I grew up in the Willamette Valley so hopefully I can help. If you're thinking of central Oregon than either the Deschutes or Crooked would both be good bets. The Metolius is a nice, scenic river, but the fish can be very picky at times, so bring your best game if you head there. As I said, those rivers are in Central Oregon and will require going over the pass towards Bend.
In the valley, you can try the Santiam rivers, just east of Salem. They've made some good changes on the rivers there, no longer stocking them with hatchery fish in most places and letting the wild fish take over again. Very little pressure as bait isn't allowed in many areas.
The upper Clackamas river, above Estacada is also an option. If you're as far south as Eugene then you definitely want to hit the Mckenzie river - rainbows and cutthroats are pretty plentiful on dries here.