The hard part about riding powder on Blue runs, is that it's generally not very steep and you don't get very much speed. When riding powder, speed is your friend because the shit loves to constantly try and slow you down. The slower you are going the harder it's going to be to make a turn. I find that when I'm riding powder on a mellow slope, I have to put way more weight on my back foot to keep myself afloat because of the lack of speed, so the steepness of the terrain is probably something that is tributing to having to ride in the back seat all the time.
Another condition that affects how you ride powder is the powder itself. For example, when riding deep wet-powder,(Sierra Cement) it almost feels like the snow is trying to pull you down. Once your nose falters in, your screwed because the stuff is so heavy and wet it will just make you do a cartwheel. On a the flipside, a thin, 3-8 inch layer of Sierra Cement acts completely differently because there is a packed base underneath it, causing a huge reduction in the sinking-suction effect. A thin layer of Sierra Cement is one of my favorite things to ride before it gets chewed up, it's like riding on a stick of soft butter.
Light and Dry powder also acts completely different. This type of powder doesn't compact very well, and it's density is so low that you will sink in it, but it will not grab you because it's too light. You can ride this kind of powder all day long even when it's chopped up because it never compacts very much.
Some things that I would suggest to help you not have to ride in the backseat so much is to give yourself a stance-setback on your board, 2+ inches if you are having a hard time right now. Like I stated earlier as well, try and get as much speed as possible when riding into powder and avoid making big wide turns when you are on mellow slopes, because it will kill your speed and cause you to start sinking.
PowderHound and TreeNinja