This was a shorter stop than I'd thought it would be. The self-guided tour starts in a gift shop that we breezed through so I don't know what's there. An employee was handing out free M&M samples though...had to partake.
The tour is basically a long hallway with some signage about the factory floor, which you can see though the large windows. Not much was going on when we visited (watching 2 women sort though lollypop sticks wasn't too exciting) and the signs give a basic description of what the machines are, etc. At then end of the hallway, there's a booth with a guy handing out chocolate samples. Just plain chocolate though, not any of the fancy truffles. It was good chocolate... :-) I didn't realize that Ethel M chocolate is related to M&Ms - the founder was one of the Mars family that runs that empire.
The tour ends in the gift shop, where you can buy all the Ethel M chocolate your arteries can handle. We did not buy any because we were in a car, in summer, and were not heading back to our hotel right away. Otherwise we'd be left with a puddle of Ethel M chocolate, which isn't quite as tasty.
The cactus garden outside was pretty cool though. Cool to look at, not cool to be in, since it was blazing hot at 10:30am already and cactuses don't give off much shade. Highlight of the day: my son touched one of the cactuses to see how sharp/soft it was, and he barely touched it but had a million prickles in his fingers. We laughed pretty hard at that, because DUH, don't touch the cactus! Lot of fun shapes, and I particularly liked the cactus skeletons.