We're all wired a little different. Sometimes its; hands forward, hip forward, edge awareness, playing w/ turn radius, comfort on terrain and conditions. What ever works. My biggest breakthough was more ankle flex.
IMO, from what I see in the slope, the differences between the intermediates to the advance is both hip forward and ankle flex. Without these, you can't make those pretty turns.
Totally agree... and when you're teaching you have to be careful to say what you mean.
"Lean forward" might get you a bow instead of hips forward.
"Hips forward" without ankle flex will lead to "in the backseat".
"Bend your knees" without ankle flex leads to "in the backseat".
"Hands up" without hips forward and ankle flex lead to exactly what Mattchuck describes.
The key combo of "hips up and forward, hands up, knees and ankles equally flexed" is the athletic stance you want.
But it's awfully hard to teach all that and make it all stick in one lesson. At the intermediate going to advanced level, small victories are the goal because they all lead to improvement and the sum leads to advanced skiing.