We drove from ND to OR (20 hours) this summer. DH wanted me to have paci's just in case. DD2 cried 18 of those 20 hours and a paci did not help because to her, it was just another toy. She does try to take other baby's paci's though. I guess she thinks because she doesn't have one, they shouldn't either.
Re: Evertime I put a pacifier in DS's mouth
He will occassionally gag too, but the irritated/PO'd look seems to be his favorite lately!