Big Sur is, coarsely speaking, the stretch of coastline between Morro Bay and Monterey. Route 1 hugs the coast, and there's cliffs down to the ocean on one side, and mountains and an occasional canyon to the other side. Hearst Castle, the Bixby (Creek) Bridge are here, as well as a few state parks, ocean-bound waterfalls (rare), a lighthouse on a rock (Point Sur); it's quite fascinating. Plus you arrive at Carmel, Pebble Beach, Pacific Grove, and Monterey, which are scenic in their own right.
After that, go to Santa Cruz. The Henry Cowell Redwoods State Park is the southernmost redwoods park on the coast. It's not quite as impressive as the Redwoods National Park much, much, much further north, but it's got the trees and the atmosphere. You're still south of San Francisco at this point. You can take Route 9 (a winding road) or Route 17 (a less-winding road) up to Silicon Valley from Santa Cruz.
After that, go to Santa Cruz. The Henry Cowell Redwoods State Park is the southernmost redwoods park on the coast. It's not quite as impressive as the Redwoods National Park much, much, much further north, but it's got the trees and the atmosphere. You're still south of San Francisco at this point. You can take Route 9 (a winding road) or Route 17 (a less-winding road) up to Silicon Valley from Santa Cruz.