Why do hackers build applications without having a distribution strategy? You can build the best application ever, but if no one finds it you are going to have the issue you have now.

Before even starting a project like this you need to be asking 2 questions.

1. Is this an application that is going to really solve a problem people have? 2. After building the application is there a viable distribution strategy for it?

I know that doesn't directly answer your question on how to grow your audience, but I think the question you are asking is something most hackers overlook and maybe this will help others still deciding on what they want to do.

To directly address your question, I would seek out and open conversations up with sites like Gusto and other social travel sites. You might be able to piggy back off of their audience or become a potential partner or acquisition option for someone a bit more established.