I'm not from there, but when traveling there as a student I remember the Huntington Botanic Garden as being fabulous. Great museum/library too, I think.

Santa Barbara has a couple must-see sites as well.

Go to the gardens at San Juan Capistrano. It's a beautiful small town between LA and San Diego. There is an Spanish church with gorgeous gardens. The town has many older houses, some are now antique shops.

Hope this helps!

Dan