Parking lights which stayed on with the head lights didn't come about until around 68 (IIRC). Having owned several 64 - 66 GM products, I know for a fact that if your 66 has the original head light switch, the park lights will go out when you turn the head lights on.
Wiggle the door switch. Make sure the wire is attached to the back. Make sure there is no corrosion around the switch. (I am a little fuzzy on this one. IIRC, they are grounding switches.)