Anything can work if you can convince the search engines to rank your site on top for most of your targeted keywords. Just take a look at this list. That page tells you a rough idea of most the high paying keywords. Do not follow the US$XX things. It might not be correct.
Worry less about finding keywords that pay well now, and more on a topic you actually know and have a passion for, so that you'll be more inclined to stick with the site's development in the future. Keyword popularity can come and go in a heartbeat depending on what happens in the world. Don't buy into fads. Think about your longterm goals, and what efforts you can maintain over time while reaching them.
Travel sites... you should cover this topic. My site is a travel site also.. specifically provides discounted hotel rental.
finding good keyword requires some research. you have to make a balance between pay per click for the keyword and the competition in the market. You can use google trends, overture and similar tool to find the right keywords for you.
Build a site with the content u r interested in.thats the most important.When the traffic goes up,you could earn a lot as u wish
Research, target, niche, and make it enjoyable. One advice that was given to me starting out was pick something you can talk or write about forever! That's a great start, and then you will not only see it how it works, gives you a good start, and most of makes it enjoyable for all!