Spending a full day at Hollister Hills you could run all of the trails. The play areas are fun to goof of in too. Jungle trail used to be my favorite, but over the years its become more like Tank Trap.
The best possible bit of advice I can give you is DONT TOUCH ANYTHING GREEN
I dont care if its poison oak or not. Do not touch any plants or bushes. And don't touch the outside of your Jeep if you drive through bushes on the trail. Poison oak is a bitch, but my kids and I have never gotten it following those rules
Been going there since the 80s and I have friends that get it every time.