I still think Orbitz has the best layout and the advantage of searching web fares more thouroughly than Expedia or travelocity.

As for SW, they tend to have the cheapest routes when they enter a market and then slowly increase them. Compared to some of the smaller economy airlines and the major airlines on their cheapest routes, they are often no longer the cheapest option. I bet SW did not want that made obvious on a layout such as Orbitz which clearly displays the price options.