I've had the problem of spotting the airfield too, and I'm not just talking grass, I couldn't see Sheffield with the lights on!!!
One thing I have thought of, but not tried out yet, is using Google earth. You could find the strip you want on there then you can tilt and rotate it into the direction you expect to come from. This way you could see where the strip lies in relation to other landmarks.
If anyone has tried this, does it work in practice?
Ben