I live in San Francisco where we have the Conservatory of Flowers for $6 entry. Allan Gardens rivals our conservatory in quality and it's FREE! If you are in the area and love gardening and/or nature this should definitely be on your to do list.
I wish more plants had name plates so we could know what our favorites are called. Seems like they are in the process of working on that feature.
There is also a dog park located just outside of the gardens, should you wish to bring your furry friends :)