Hey, right now I'm looking for ways to market adspace on my traveling site. It's already getting pretty much traffic but still not able to sell ads or to find somebody who is willing to advertiste on my site.
As far as my experience goes , You need to use social networks like twitter and digg to attract people to your travel site and if its really good looking and attractive then people would definitely like it.
You probably need more traffic before any advertiser willing to place their ads on your site. You can always use Google AdSense for the time being.