Klamath Falls, OR to Mare Island Ferry (San Francisco Bay)

A pleasureable route that is mostly either flat or downhill -- the exception being the decent climb up to Clear Lake out of Williams, CA, followed by another short climb over to Calistoga.  The trip was done in September, which made for an enjoyable ride through Napa.  On the downside....  First, once one enters the upper Sacramento Valley (Redding), head winds originating from the Bay are a constant companion.  Not strong enough to make the ride unpleasant, but enough to deny you a leisurely stride on what is essentially a flat surface.  Secondly -- and far more importantly -- the only route from Mt. Shasta to Redding is on Interstate 5.  The shoulder is easily wide enough to put a decent buffer between the rider and the alert driver, with the exception of the two bridges across Lake Shasta itself.  The bridges offer no shoulder to speak of, and one quickly crosses hoping that the drivers are, in fact, particularly alert on this stretch.  Needless to say, the I-5 segment is noisy and dirty; a serious mar on the route as a whole.  On a scale of 1 to 10, 10 being a fantastic trip, I would rate this one a 7; it would be a 9 if not for the I-5 segment.  If you are interested, you can train up to Klamath Falls (which is what we did).  The train arrives about 8:30AM, giving you the ability to hit the road right from the get-go.