The rose garden, which my mom came for, wasn't really my cup of tea, but I found the sign explaining the development of the hybrid tea roses (the most popular rose varieties aren't naturally occurring) pretty interesting. Saw a lot of small lizards throughout the garden. We also checked out the area devoted to food crops of the word pretty thoroughly, before they announced that the garden was closing.
Incidentally, the Botanical Garden is up on a hill, near Lawrence Berkeley Lab (of Nukees fame) and the Lawrence Hall of Science (where I spent a great deal of time as a kid). Before going into the park, I saw this on a bumper sticker in the parking lot:
Cryonicists stay stiff longer