This is a 7.4 mile out-and-back hike popularly known for its photo op on a unique rock formation that will make your mom nervous.
This is an amazing zoo, do know that there is a second part to the zoo in down town San Diego that is also cool but can be confusing when getting directions.
This area is a quaint park offering vintage train rides and a Saturday farmer's market.
The city of Julian is well known for their apples and their apple pie. While it's a little out of the way, but 100% worth the trip.
You're in Southern California, you should go to the beach. This is a good one to stop by with big green spaces and beach access.
If you're into theme parks but aren't trying to pay Disneyland prices or make the drive up there, Legoland is the place for you. Also, there's supposedly a lego themed water park you can check out.
This area and North up to Temecula area are well known for their wine. While I do not have one particular winery to recommend, I do encourage you to research around and find a few to try. Some of them are only open certain hours, so plan accordingly.