I've spend over 20 hours per week on ellipticals for over a month before. One of the major aspects of my approach to exercise is "quantify everything mercilessly," and having readouts for how fast I'm going, heartrate, calorie burn, etc. made it more attractive than just running outdoors.

(I'll note that I don't consider this to have been particularly sane behavior; it was accompanied by some extremely harsh diet restrictions, and it probably had a lot to do with a resurfacing of old eating disorder habits.)

I wouldn't play music or anything while using them, I would just zone out, and let the whole experience blur together. It made the sessions feel much shorter in retrospect than they actually were.

I generally use treadmills instead when they're available, but running outdoors is pretty near the bottom of my list for enjoyable forms of exercise.