I don't give out many 5 stars, and I'm tempted to do so for Hwy 3. If you ride it north from Hwy 36, you'll see why I like it pretty quickly. If you ride it south from from Yreka, you may wonder what all the excitement is about until you get beyond Etna. Then things get REAL interesting. There are at least two significant mountain passes between Etna and Hwy 3 (going by memory), and they'll both keep you fully engaged.
Between the area around Trinity Lake and Weaverville you should expect to encounter law enforcement, but much south of Weaverville things get fun again as you head over Hayfork Pass. The next thing you know you end up smack dab in the middle of Hwy 36, one of the best motorcycle roads in the state. Life is very, very good!
The triangle made up of Highways 3, 36 and 96 - plus a bunch of the roads that branch off of them - should be on your must ride list.
Really nice and twisty southbound alternative to I-5