Comparing indoor versus outdoor running

I was out of the office most of last week for the Thanksgiving break. Days off give me more time to run outside and I think that it's important to balance indoor treadmill running with pavement running. The experiences are very different, the view on the treadmill (Pro-Form L18) doesn't change (unless TV counts) while my outdoor runs are almost always unique in terms of route. The treadmill is a more forgiving and enabling process since the tread itself is more padded than pavement and the motion of the tread provides momentum for the runner. On the other hand outdoor running provides a variety of conditions (elevations, weather, terrain) that can be positive (or negative) distractions.