Let 'er Rip
Heading south, you won't hit as many technical roads, but you will have some of the best weather and greenery that any of the motorcyclists heading to the Sierra Stake Out will find.
If you like a good beer, take a pit stop in Bend, OR to check out their selections from around the area. Once you get past there, you'll have to decide whether to head down the 31 or 97. You really can't go wrong with either route as both pass by several national forests and lots of swimming holes.
Take your time over the last few miles. The 89, 49 and 70 all provide great conclusions to your journey.