I was on 36 last week and although it is a challenging ride, the scenery is great.
Another even more challenging ride is Hwy 162/Forest Route 7 through the Mendocino Natl Forest. I did that in June from east to west. It starts just N of Willitts. The ride to Covelo is nice and then again to Eel River Station which will be the last services before Elk Creek. From ERS it's 15 miles up to the top which is at 7000 ft. There's a campground just past the highest point. 40 miles are hard packed gravel with almost no traffic.going down the east side you will have a long, long and mostly gradual descent, similar to 36. This route would mean you wouldn't have to backtrack as much.