A great use for GE is to pre-visualize an approach into an unknown airfield, especially if it's a small field w/o any navaids. By using the 'tilt' feature, you can position yourself on the approach and get an idea of the 'picture'. I've used this a lot when flying in Africa or Oz, where strips often totally blend into the surrounding landscape (in fact, you could say the same for small grass strips in the UK - it's just greener!).
I also use the overlay derived from my GPS data after a flight. Don't use it much for enroute flight planning, prefer the charts for that, either paper or electronic.