Get an ExpertFlyer subscription. Read the fare rules for your airport pair, all dates, cheapest to most expensive, until you find a set of restrictions you can live with. (Yes, it's probably a Sat night stay that's getting you.) Sticking it to business travelers has been the goal of airline Revenue Management since fares were deregulated forty years ago. Business travelers are thought of as generally insensitive to price - spending other people's money, as it were.