Here's some simplified directions:
880-->85--->Saratoga Blvd--->Hwy 9--->summit
Here's the loop I was thinking about.
Meet at the Summit, and drive all the way down 9 to Santa Cruz. Turn north on HWY 1.
Go right on Bonny Doon Road, from B.D. road, we would turn right onto Smith Grade. Take Smith Grade to Empire Grade and go left(north). From Empire Grade we would turn right onto Jamison Creek road. Down Jamison Creek rd. until we end up at Big Basin Hwy. Right on Big Basin Hwy. until it ends in Boulder Creek. From Boulder Creek, we just take a left and cruise up HWY 9 until we are back where we started.
Total time: I'm guessing 1-1/2 to 2 hours max.