We are headed to San Francisco this weekend. While there, I'm planning to drive to Monterrey to take the kids to the aquarium. Is it too far a reach to think we can also drive to San Simeon on the same day?

Kinda doubtful on the same day in that it is about 92 miles each way from Monterey.

Yes, if only because the basic tour of San Simeon will consume about three hours by itself (waiting for the shuttle, taking the shuttle, taking the tour, taking the shuttle back to the parking lot).

If you are planning to stay the night near San Simeon, then you can drive from SF to Monterey, see the aquarium, and then drive to San Simeon in the same day.

Its 1 1/2 to 2 hours from SF to Monterey, and then probably 2 1/2 hours to San Simeon, not including stops. You will arrive in San Simeon late in the afternoon, so visiting Hearst Castle that day would definitely be a stretch.

If you wanted to make this a 2 day trip, you could see Hearst Castle the next morning and then head back up to SF via Hwy 101.

With only 1 day, San Simeon is too far from SF.

Thanks to all who replied. It's helpful to know this.