Hey Craig thats my neck of the woods. We will be here in McKinleyville (right next door to Arcata) for Christmas so we should get together and have a beer. The trip up the Salmon will be real nice assuming we don't get a really low snow. There are lots of side trips to do up there and lots to explore.
If I could make a few recommendations....Take 299 to Redwood Valley Rd (Bair Rd) and follow down into Redwood Cr. Once on the valley floor look for the intersection of Bair Rd and Stover Rd. Bair Rd takes a right and turns into dirt. This road travels through some beautiful country that only the locals really see (Miner Cr and Supply Cr). Right now the road is passable but snow will close it eventually. The road eventually lands you on the Hoopa Reservation (Hwy 96) and the Trinity River. Continuing up 96 you have a few options for exploration (Bluff Creek for example) before you hit Somes Bar. In Somes Bar you will take a right on Salmon River Rd (93) which goes up the mainstem of the Cal Salmon. There is a lot of good geology here and I would highly recommend a hike up Wooley Cr and taking time to check out the Class V rapids on the Salmon. There are numerous campgrounds as you go up the Salmon as well as roads that you can explore to get to more primitive spots. Once you hit Forks of the Salmon you can either go up the NF or the SF of the Salmon. I know you said you were going to go up the NF but I would suggest going up the SF (still the 93) toward Callahan. Again there are campgrounds up the SF and places to explore. Once you hit Callahan you can hook up with Hwy 3 and either go back to Interstate 5 or take Hwy3 over Scott Mountain summit and down the upper Trinity River. There are plenty of places to camp going down Hwy 3 and its a gorgeous drive. Hwy 3 will eventually land you in Weaverville back on the 299, which you can take east to Hwy 5 or west back to the coast. I have done this loop more times than I can count and never get sick of it. You will be traveling in some pretty remote country and will likely be by yourself most of the time.
A lot of this trip is snow dependent but I have done it this time of year and had no problems (though I have had to chain up in 4-wheel drive). All of the roads up the Salmon and down the Trinity are plowed on occasion and locals use them to commute so they usually don't close for more than a day or so.
I was just talking to the boss (wife) and she said that she would not mind me taking off for a few day....I would have to check my work schedule but I don't think it would be a problem. I wouldn't mind joining you if you feel like having a another rig along.
If you want to chat or want more details feel free to drop me a PM and we can exchange numbers.
Cort