The next best kept secret of the travel industry is- online travel retailers display what they want to display. Here's a great example. A recent search on a major online retailer showed a very low fare from Toronto to Los Angeles. 2 catches- Northwest and through Detroit. Nobody from Toronto would take Northwest to Los Angeles through Detroit. Worse still, if you decided you would take this flight (because of the price), and clicked through to purchase it, it was not available. Secret #2- most online retailers do an inventory refresh every 4-6 hours. (The low fare was available to a few but maybe not available for several hours).
Back to the first point- the select inventory and display. American Airlines is attepting to launch a new direct connect booking system (like a private booking site). Orbitz is no longer displaying American because of a dispute related to this program. Now Expedia is joining the fray. Expedia has stopped listing American fares in its initial fare search results (i.e. your first search results). You have to make an extra click and search for American fares.
So, a couple of bits of advice- buy what you want to buy (NW stopping in Detroit for 4 hours on the way to L.A.?) and realize you may not be getting the full picture.
