I think there are a couple of tours like Cycle Oregon.

RAGBRAI?

There is also the STP (Seattle to Portland) ride that is just 2 days.

If the OP is coming up from California, there is also "Ride the Rim". Just a single day event riding around Crater Lake, with half the lake closed off. And, it should still be open as I don't think they're restricting riders. Camp at Diamond Lake, then spend a day or two playing around Crater Lake, then another day playing around Diamond Lake.