I always wonder why folks pull the power back. No need until you're joining the flow of the pattern, other than airspeed limitations of the aircraft or legal speed limitations.
Probably like a lot of pilots I was taught to pull the power back and descend at cruise speed, but I recently changed to leaving the throttle mostly alone and pitching down. It is the only time I can get the C-152 speed into the yellow arc.
But - in a fixed pitch prop plane - I wonder how wise it is to lose altitude at a speed that pushes the RPMs much above the tach's red line.
Oh - and as to the OP's question - lately I've been using (and enjoying) the feature in WingX that gives me a constant update on the descent rate I would need to reach my destination's field elevation from my current elevation.
