Younger people use social media. Older people not so much...unfortunately they're the ones spending the most on travel.
Do you want to ignore them?
Not everyone participates in social media, at least not at levels that are commensurate with the population. Younger people are over-represented and older segments are under-represented, sometimes dramatically. To begin with, only 56% of the US population participates in social media.* And for adults over 50, the number falls to just 20%! Do you really want to miss hearing from 80% of the people who spend more money on hospitality than any other segment?
A survey-based approach, on the other hand, allows you to invite every single customer to complete a survey. Most can be completed online. But the important thing is that everyone can be accommodated - send a simple text survey to their phone, hand them an iPad with an open link, you can even give them a paper comment card if you have to. The important thing is that you can hear from everyone, not just those who happen to participate in social media.
*The Pew Research Center's Internet & American Life Project's Tracking Survey conducted July 16-August 7, 2012