I've riden 97 from Klamath Falls to Madras Oregon & found it to be boring with tons of traffic. We finally headed West to Portland because we culdn't take it any more. I believe 97 through Washington to be quite nice, but I haven't tried it yet. I5, as you know is as boring as s**t.
If it were me I'd head out to the coast from Redding. Hwy 101 in Northern California is quite nice. Stop at Rolf's on the North side of Orick for a meal, (It's a motel with a great Restaraunt attached to it).
Hwy 101 along the Oregon Coast is great before July. After that the traffic gets pretty heavy, but at least the scenery is great. Crossing the mouth of the Columbia River at the Oregon Washington border is pretty amazing. I can't remember the length of the bridge, but I belive the crossing is well over a mile long.
Roads along the Washington coast are not overly inspiring, so you might like to head inland once you're in Washington. If you have time, there are some GREAT roads around the East side of Mt St. Helens & Mt Ranier or hook up with Hwy 97 or it's about a 2 to 2 1/2 hour blast up I5 to the Canadian border from Seattle, which isn't too bad.
Once you're in BC there aren't too many options... Head for Prince George & turn left on Hwy 16, then right on to the Cassiar Hwy (37) at Kitwanga. There's a big gas station at the Junction at Kitwanga (Esso or Petrocan I believe). Be sure you have at least half a tank of gas or gas up there. The road from Miziadin Junction to Stewart/Hyder is nice with a great view of the Bear Glacier. I've gone well North of Miziadin Junction on my KLR650, but I wouldn't do it on my FJR, too much gravel for the FJR for my taste. Be warned the mosquitoes anywhere North of Kitwanga are small, but they're like Piranahs, (not so bad in town). I'm told they made them small so they could get more in
On the way home, if you head West on Hwy 16, Prince Rupert is pretty nice. Up until a month or two ago you could take an all day ferry ride from Prince Rupert to the North end of Vancouver Island. It left early in the monring & arrived around 10:00 PM. It was a really nice ship or so I thought until it SUNK recently, (yes sunk). I believe there were about 100 people on board, (which was much less than capacity). All but 2 made it off & the 2 are presumed to have gone down with the ship.
I'm not sure what will be running on that route now, but if you intend to pursue that route you should book in advance... www.bcferries.bc.ca If you don't get on a ferry it's a "dead end" though & you must back track. I'd estimate about 2 or 3 hours from Kitwanga to PR.
If you do manage to catch a ferry, it's a nice ride down the Island, with a few options to get off at the mid to bottom end.
Anyway, hope that gives you some ideas. Watch for wildlife in Northern BC, especially after dusk.