Depends on when you are going and what you are riding - -
An inland route can be really sweet - far less traffic - lots of free camping. But roads at Crater Lake and Mount Lassen don't open until late June, even July. This year might be a little earlier. Also, a mountain bike allows you many, many more options on the interior route. I have found that, although the riding is easy in the Willamette and Sacramento valleys, the scenery is only so-so and camping can be hard to find and expensive. (i.e. Winnebagoland) The east side is MUCH better, but avoid US 97.
A real nice route would be Mt. Ranier, Mt Adams, Hood RIver, Bend, Mt Batchelor Loop, Crater Lake, Mt. Shasta, Mt. Lassen, then cutting thru Chico, Colusa, Calistoga to end up at Golden Gate Bridge.