Rt. 66 is a historic highway, or what's left of it. So what it's worth to you as a tour depends on what you want to get out of it. There is the nostalgia thing, I guess, but there's not much left of the original road, most of it now being interstates. The best section to ride is in Arizona, for about 200 miles. Otherwise, I think you will be disappointed.
I agree, Hwy 101/PCH is a good ride, but there is a lot of traffic and it goes through a lot of urban and suburban areas, with lots of traffic lights along the southern-most section, from San Diego to just north of L.A. Best bet, IMO, would be to pick up 101 through San Francisco, go over the Golden Gate Bridge into Sausalito, then pick up Hwy 1 to the coast. You'll be in for some great twisty roads and a nice ride up the coast. You can take Hwy 1 for a long distance, but just north of Ft. Bragg, CA, it joins up with Hwy 101. You don't want to miss riding through the Avenue of the Giants Redwoods park. It's amazing.
At Eureka, you can pick up Hwy 299 and go east to Redding, CA. I can't say that Redding is that much of a destination, but 299 is a great ride. Besides, east of Redding you can continue on 299 and visit Lassen Volcanic Nat'l Park. Amazing roads and scenery there. You can double back and come out at Mt. Shasta and then exit at Weed, riding up U.S. 97 through Klamath Falls, OR. You won't want to miss riding up to Crater Lake. And while you're up there that far, you can continue your ride up toward Portland and ride the Columbia Gorge. Even on I-84 it's a great ride.
I guess there's lots of good roads to ride, and I could go on and on, but the the end result is that while Rt. 66 is a historic ride, it's not "all that" anymore.
"Don't sweat the small stuff---it's all small stuff"
'09 650 VStrom