As promised, here are some photos from my most recent visit to Stanford's Arizona Garden, which has many, many, many varieties of cacti and other succulents, including agaves and aeoniums. The garden isn't huge, but it's well-maintained and worth a visit. Nothing there is labeled, but in some of these pictures, I'm venturing a guess. If you click on the smaller pictures, you can see a larger version.
(If you're in Palo Alto checking out the Arizona Garden, I recommend checking out the Gamble Garden as well. It's just a 5- or 10-minute drive away.) Have any of you ever been to the Arizona Garden? What did you think of it? Any other must-stop succulent destinations on the peninsula?