Generally a copperhead or rattlesnake won't bite more than 6 inches above the ankle. Most often they will do eveything they can to get out of your way. Snakes don't hear or see very well at all but feel vibration from your footsteps and see movement. Unfortunatly, your best chance of being bitten is while you are still hunting or walking very quietly to and from your stand. When you sneak up on one by accident, the snake will bite out of fear.

I prefer snake boots over chaps. If you wear rubber boots the chaps will not protect your toes as the fangs of a fair sized snake will go right through a pair of rubber boots. The only advantage to the chaps would be if you walked by a snake that was sitting on a rock or stump that could put them high enough to bite above the boots.