Even with kids, going through as fast as we dared, we still spent 5 hours there (including lunch). We didn't expect to spend that long there, so we ended up skipping the waterfalls at Limekiln State Park and we arrived at Big Sur right around 7 pm. We did make sure to stop at McWay Falls, but that was maybe 30 minutes short of Big Sur. It made for a long day (Moro Bay to Big Sur).

There's an enormous gap in civilization between San Simeon and Big Sur, nowhere really to stay. So make sure you schedule accordingly. Everywhere else along the route has intermittent towns, so it's not as difficult to plan.