CA Zoners - pls weigh in

If you go N. on 101, with its seascapes and redwoods, why  not make the return trip S. on the back side of the Cascades/Sierras on Rt. 97/395 and check out the deserts and mountains?

If you drive back on the east side like Surfdead offers, I'd suggest driving to the top of Paulina Peak, a short detour off the HW takes you on a paved road to the top of a just shy of an 8k foot mountain, with spectacular views of the Cascades, Fort Rock, Steins Mt, with views of Mt Shasta to Mt Rainier, it's just south of Bend... and the 2 lakes in Newberry crater have hot springs, but recent development makes them harder to find...  There's also lava caves, obsidian flows, many things to see there! 

Lots of great concerts in Bend these days, if lucky can coordinate a good show!  

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If you visit Crater Lake, there's abundant camping at Natural Bridges (where the Rogue River goes underground into a lava cave), and Union Creek campgrounds.  Lassen Volcano might be a bit off course, but another geologically interesting area (mud pots, etc).  I figure there's abundant greenery on the coastal drive up north from San Francisco, except for the wine, lol...   (Boonville had some cool wineries, old motels, etc) 

As to concerts in Bend, Oregon; 

https://www.bendconcerts.com/events-concerts

https://www.towertheatre.org/

https://www.volcanictheatre.com/calendar

There's food courts with music too, several other spots...   been a few years since i've been out there, so my knowledge is dated 

Where the Klamath River meets the sea

a friend recommends the jet boat tour there

Jet boat tours also available on the Rogue River at Gold Beach, Oregon.

We stayed in St Orres in Gualala and Little River Inn before. Cool areas. 

>>>>Any advice on a route to take back down from OR to CA?

From Portland, consider heading east on I-84 and check out the Columbia River Gorge.  Then in Hood River, take Hwy 30 south until it meets up with Hwy 26 at Mt. Hood.   Then continue on Hwy 26 until it meets up with Hwy 97 at Madras and head south to Smith Rock and Bend.   From Bend, you can then head south to Crater Lake.   From there, make your way over to I-5 and you are only about five hours from SF with possible stops in Ashland, Mt. Shasta, and Lassen.

Lodging in Crater Lake is limited, but if you try to book now, you might get lucky and get a room at the old lodge right on the south rim of the crater.

For lodging on your way up 101 in Northern California, check out this funky AirBnB in Arcata:

https://www.airbnb.com/rooms/31449493?c=.pi80.pkYm9va2luZy92Ml9taWdyYXRp...

We just stayed there last month coming back from Phil at the Warfield.  Soaking in the outdoor tubs under California stars was a real treat.

"Hoping to drive 3-4 hours per day"

That will make for a much more enjoyable trip. It is a long journey along the California-Oregon coast.

Powell's Bookstore in Portland is a must visit.

If you still have the gumption on the return journey, Hwy 395 is a scenic route indeed. If you take I-5 back to the Bay Area, be sure to stop by YAKS on the 5 in Dunsmuir ~ Just because.

Hope the weather is good and that you have a wonderful time.

>>>>Hwy 395 is a scenic route indeed. 

I was going to suggest Hwy 395 as an alternative.  It is scenic indeed, especially from La Pine to Lakeview near the Oregon-California border, but it is a little out of the way if you are headed back to the Bay Area.  Please note that this route is very remote until you get near Reno and is punctuated by only a few small towns every now and then, so plan food and gas stops accordingly.  If you do take that route, consider stopping the night at Summer Lake Hot Springs:   https://www.summerlakehotsprings.com/    It's sort of a low rent Breitenbush but still pretty chill place to soak and watch the sunset over the high desert. 

Crater lake is off the path but a place I enjoyed

On the way up for three nights: Mendo, Arcata, Seaside