KSC is the closest you can get (4 miles). The best view however is the KSC causeway (6miles). From KSC you can hear the launch however. Unreal sound, but not terribly loud like an airshow.
As to the distances, in one of the presentations they state that at 400 feet, the heat will kill you instantly, at 800 feet the sound will kill you instantly. At 2000 feet, the shock waves cause the alligators and snakes to attack anything that moves (killing you instantly :chuckles
. They say that the closest safe distance is 3 miles i guess b/c the amount of fuel exploding = atomic bomb blast.