Have done a bit of checking into CA-299 btw Redding and Arcata WRT traffic. Many riders have pointed out that there's traffic on CA-299 while CA-36 has very little, and suggest blowing off CA-299, which is often regarded as being more scenic, for that reason.
CA-299 definately has more traffic, which can be quite bad, during the summer weekends. However, weekday traffic isn't in the same category, and once west of Weaverville, it dwindles quite a bit.
The road is fairly wide so passing is easy which is a good thing, but the CHP has a branch office in Weaverville, and the CHP patrolling US-101 btw Eureka and McKinleyville also cover CA-299 to Redwood Creek.
At my end, we'll be riding west on CA-299 from Redding to Arcata on Monday, June 25th sometime after lunch.