Kellen and I both think the Wild Animal Park is more unique then the San Diego Zoo - but both are really nice to visit. You will need a car to get to the Wild Animal Park.
They offer dinner cruises and day time tours of the harbor.
Whale watching can be hit or miss in October. Peak Season is usually December - April. But they also offer lovely tours of the harbor and dinner time cruises.
La Jolla Cove is famous for kayaking and Sea Lions. There are lots of shops and restaurants around this area as well. You can snorkel and swim in this area as well.
There are several companies that offer kayaking tours or rentals! Highly recommend this activity.
Beautiful State Park with several "easy" and "moderate" intensity hiking trails.
Annie's Canyon: Unique for it's slot canyons. Overall an easy trail.
Other cool hikes: Potato Chip Rock and Sunset Cliffs.
One of our favorite "nicer" taco spots. We love the filet mignon taco, tamarindo shrimp, and short rib quesabirria.
There are several stone brewery locations around San Diego. This is one of the larger ones, but all locations are nice!
If you are going to the Safari Park in Escondido - there is also a great location near there.
You can also do an organized brewery tour if you want to try multiple spots.