I've run across some of the biggest Rattlers I've ever seen hiking and running in the Santa Monicas near Mulholland Drive, right near all the mansions.
My wife works with DFG and runs into them pretty often, some really big. She's never had a problem, but wears leather boot gaiters. The biggest ratter she ran across while working was one near Riverside. She said it was laying on a rock, then left when it saw her. She was curious and went back later to find it laying on a very large boulder. She stayed for a while and photographed it. She estimated it to be near 6 feet, which would be the biggest of the species (I don't remember which species.) It had 13 rattles!
Here's a pic of her snake:
Here's a pic of one her partner ran into. It wasn't as friendly as seen in her photo. She almost ran into it and had enough time to take her camera out for this shot:
My field trail German Shorthaired Pointer was killed by a rattler years ago, during competition, when she stopped to point and was struck in the tongue. She suffocated.
"Turtles, Frogs & other Environmental Sculpture"