We were travelling for business from EU. My feeling was that those of us who were travelling most frequently were pulled, but apart from slight inconvenience it ended OK. We started placing bets who will it be this time :) I always had paperwork ready, letter from business I was visiting, hotel booking, phone number to business rep who would confirm my credentials, but I was never asked to produce them. Though, I don't know about travelling with family, I am not much of a touristy guy..