I'm hoping to spend 3 weeks on a solo journey in Northern CA this June. I live in SF so would like to do a loop from the city and back. I'll be doing the Climate Ride from Fortuna to SF (mostly down the 1) beforehand so I'd like to do something different and a bit more inland through Sonoma, Mendocino, Shasta and even southern Oregon if possible.
As a homebrewer, I'm also interested in exploring some breweries but would also like to be a bit more off the beaten path (hopefully these aren't mutually exclusive)
I've got the Krebs maps on the way but wanted to get your input! Any ideas for a good loop for 3 weeks or so (let's say around 65 mi/day)?
Bruce Gordon Ti Rock N Road , Fat Chance Mountain Tandem 
Look for California Dream Cycling by Bodfish for a variety of rides suggestions in the N. California inland portion of the guide. If you are including off pavement route get Bodfish's Cycling the California Outback. Again with many outlines of options in your desired territory.
You can find them at Bodfish Cycles in Chester, California at Lake Almanor. The owner of the shop and the writer of the guides is Chuck "Bodfish" Elliot.
Hmmm...you would probably like to head east out of SF to avoid fighting headwinds. To get to Lake Tahoe, you could take the ACA Western Express route over Carson Pass, or a more challenging ride over Ebbetts Pass on Hwy 4. Once you get east of the Sierra, it seems the wind is a lot less of a factor. Head north over Luther Pass, now on the Sierra Cascades ACA route (which I get the impression from reading journals that they don't mention a lot of the great hiker-biker sites along the way) to Tahoe, then on 89 all the way to Shasta or even further. On the way back south to SF, there's lots of back roads in the Klamath and coast ranges to explore, but maybe reading some journals on the crazyguyonabike site can give you more of an idea there.