A comprehensive list of local Monterey Bay coastal activites can be found here:
http://www.thesanctuarybeachresort.com/area/activities
*Tip from Prof. Buxbaum:
Those with children may want to visit the superb Monterey Aquarium — but you should make reservations in advance to avoid the long lines in the summer season.
Website: http://www.montereybayaquarium.org/
You will find a lovely mission site easily reached if you return Sunday on Highway 101 is San Juan Bautista, just a mile from the Hollister exit. The mission is an active church, but services typically are over by noon. There is a pleasant Mexican restaurant, with outdoor patio seating, just off the plaza.
Mission San Juan Bautista Website: http://oldmissionsjb.org/index.html
Restaurant Website: http://www.jardinesrestaurant.com/