Agree with the above that the Santa Cruz area would be the place to look. Plenty of activities to keep the little one occupied for a few days. Off the top of my head:

-Santa Cruz Beach Boardwalk
-Monterey Bay Aquarium
-Roaring Camp Railroad
-Mystery Spot
-Gilroy Gardens theme park

Also pay attention to the temperature forecast and pack accordingly when you get close to the trip. The coast can be around 60°F/15°C while just 20 miles inland it could be around 85°F/28°C (or warmer) that time of year.