Getting customers to do your marketing for you is the mantra behind corporate social media these days. And among the travel industry, it seems, no PR offering  is more effective than a Twitter-based trip giveaway.

My relationship with “PR people” has morphed throughout the years. On newspaper city and suburban news desks, where I spent the first 14 years of my career, we called them “flacks,” derogatory meaning intended. To a news reporter on deadline, a PR person was, if not the enemy, then certainly...