Well, you can also do it in one layer: http://google.com/flights http://google.com/flights There is a lot of "slack" in how travel is priced due to all kinds o

Well, you can also do it in one layer: http://google.com/flights http://google.com/flights There is a lot of "slack" in how travel is priced due to all kinds of agreements about what rates you're allowed to show. That's partly why package deals can be so good. These are not simple problems to solve, even in a best-case scenario.