Some months back when this was posted https://news.ycombinator.com/item?id=17944934 , I thought about doing a POC about this topic. You could scrap a lot about tourist data from state/regional/communal websites and make travel suggestion for the least tourist plagued locations in a given area. The problem in the long run is the more successfull you are, the worse the experience will be, in short term tourism/vacation is to crowded currently to get it flying.