If you're taking either of the two bikes in your signature, don't bother with the Rubicon.
Chico is in the valley. Rubicon takes you over to the eastern side (Lake Tahoe). Highway 49 is essentially the tourist route through the gold country, following the foothills along the western slope of the Sierra.
The best route (if you're from WI) might be to run from Marin to Yosemite and take Tioga Pass (through Yosemite over to Lee Vining) and then find your way back up to the crest of the Sierra near Markleeville, turn north from there and head around/past Lake Tahoe, then over to Truckee and turn west over Donner Pass Road (small section of I-80) and come down Highway 20 (through Nevada City) and pick up Highway 49. From there, head north to Downieville, then to Bassitts and take the Gold Lakes Highway to Graeagle. Now you're on the easter side of the Sierra again. You can get to Chico (if there's someone/thing there you need to see - like the Sierra Nevada Brewery) via Highway 70 or other similar routes to Oroville and onto Chico. Then head east, back up toward Mount Lasson and follow that route north toward Mount Shasta (on the east side) and work your way up north to Oregon.
Try to follow that on a map. It's the most indirect route from A to B, but you'd cross the Sierra/Cascade Range several times and hit several small towns with a godzillion side-road routes to taunt you along the way. Lots of options to camp along this route - or not be too far from lodging if necessary (laundry time).
I've riden this entire route (over various trips) and it is all good stuff. Maybe you should tell us a bit more about your idea of an "ideal" trip so we can help you a bit?
2010 KTM 990 Adventure
2010 KTM 450 EXC