Whether you were forced to go to local day (it was free) by your parents or you were young enough to appreciate the little theme park, most have a soft spot for it. There are plenty of small rides and a few that adults can enjoy too! With gardens, circus trees (see below), restaurants, and water attractions, the park has a lot to explore. Fun fact, one of Nicole's co-workers in Oklahoma City, Alicia Clark, is the niece of Axel Erlandson - the man who originally grafted the trees in Gilroy Gardens. Below is a separate link to an online photo album of some of his work - check it out! https://www.flickr.com/groups/treetalker/pool/
If you want to go to the beach but have an iconic California experience then the Santa Cruz Beach Boardwalk is the place to go! You don't have to pay to enter, so if you want to go check it out feel free to do so. Then you can decide if you want to buy tickets for the rides or other activities. More details can be found on the website.
The Monterey Bay Aquarium is an amazing experience whether or not you have children. Please ensure to plan plenty of time for the drive (if staying near Gilroy) and to find parking. Additional details can be found on their website.