I almost suggested Hearst Castle, but I thought your plate was already pretty full. If you go, make reservations as far ahead as you can -- they fill up. Also, since you have a little one, take note that some of the tours have a lot of stairs to climb. Tour 1, the intro, is probably best. You'll burn at least 2 1/2 hours by the time you park, wait for the tour, etc. But it's a sight you'll see nowhere else.
Wow - great info here. DH and I will be doing same drive, but without the little ones (San Fran to Disneyland). We are debating the same thing - staying overnight in Monterey vs. farther south. We will be leaving from SF early am on a Saturday, checking in to Grand Californian Sunday evening.
Dreams Unlimited Travel is committed to providing you with the very best vacation planning experience possible. Our Vacation Planners are experts and will share their honest advice to help you have a magical vacation.