Bottom line if the scene is low contrast, start by increasing contrast...if the scene is high contrast, start by lowering...then adjust the rest of the sliders to taste. Or, ignore the basic panel and simply use the curve editor :~)
Jeff, curious why you would automatically want to increase contrast in a low contrast scene or reduce it in a high contrast scene. If the scene is low contrast by nature, for example over a lake or a foggy wooded area, why would you automatically want to increase the contrast in that scene? I understand your point about adjusting contrast before the other options but not as an absolute.