mtnroads

I have lived on the Peninsula most of my life and I think Nile's suggestions are very well thought out. You really don't want to miss the redwoods between Woodside and the coast - they are gorgeous. Whereas the coast highway from Half Moon Bay down to Pescadero is nothing special, so you won't be missing much. I will just elaborate a little, mostly to reinforce what Niles suggested.

I agree to go out of SFO south on the frontage road south to Millbrae Ave. Go east 1 mile to El Camino Real. At that point you can either drop south a couple blocks and go up Trousdale, a wide 4 lane boulevard, or continue up Millbrae Ave., which is winding but less steep. Either way, you want to end up right near the top of Millbrae Ave (actually 1 block north of it at the intersection of Hillcrest and Skyline Blvd), and cross under 280 to the north entrance to Sawyer Camp Trail.

Sawyer camp trail is 6 miles long and will wind down through the native flora of the area, eventually taking you along Crystal Springs Reservoir - it is very picturesque and natural since it is a protected watershed. When you come out of Sawyer Camp Trail just make a right and go across the dam and ride down Skyline Blvd along the east side of the reservoir about 3 miles to the junction of Hwy 35 (Skyline) and Hwy 92. At this point jog left about 1/2 mile to pick up Canada Rd, which takes you another 7 miles into Woodside. You can stop at Roberts Market in Woodside for something to eat and drink.

After that head down Mountain Home Road as suggested (Where Larry Ellison has his Japanese-styled estate), to Portola Rd. and up and over Old La Honda. This is my favorite route over the hill when loaded down with panniers and if I can do it, anyone can. From there you have many choices, but two that are most attractive:

1) If you want to get over to the coast asap, the best route is to go north a couple of miles to the junction of 84 and Skyline (more good food at Alice's Restaurant) and drop down Hwy 84 to the coast at San Gregorio. Easy downhill riding and nice views all the way. just before the coast highway you will also see the old Stage Rd and store. Stage Road parallels Hw1. If you take it south it will take you into the Pescadero main street where Duarte's Restaurant is. Or you can take the coast road, but there is a lot of fast traffic on it that I find disconcerting late in the day. From pescadero it is also only 5 miles of mostly level riding from there to Butano SP - an outstanding state park campground in a redwood grove. The next morning you can ride out the back way to the coast highway and continue your ride south.

2) If you want to see Big Basin Redwoods, your best bet will be to go south on Skyline Blvd to Hwy 9, then down to Big Basin, rather than taking Hwy 84 over to the coast. It will save a lot of backtracking/climbing later on to get back into Big Basin from the coast. You will travel along the spine of the coast range with outstanding views to both east and west as you travel down Skyline to Hwy 9. Hwy 9 is another mostly downhill, swooping road that takes you down into Boulder Creek and Ben Lomond, and you will want to cut off onto 236 into Big Basin. Beautiful camping, redwoods, creeks, etc. From there you are only a couple of hours from Santa Cruz.

Either way you go, have fun - it will be a beautiful ride.