Eastern diamondbacks are the biggies. The west coast ones get respectable, but I’ve seen them back east over 5 feet long.
All in all, though, they’re pretty reclusive.
I missed killing one that was over 6 feet long. He went off into the woods, down a steep hill (and I wasn't willing to chase him on his territory) while I went for the shotgun. The last one we killed was sleeping off the edge of the porch, between us and our cars. It was a fatal mistake. He was over 4 feet long and I was really surprised how heavy he was. I can't remember for sure, but I think he had 5 or 6 rattles.
You are right though, they don't like people and tend to avoid the activity that goes on around the house.