Two Main things I need.
Trails with slight hills up and down, to strengthen joints and to keep runs from not being boring.
A COLD river that swirls and moves at a a good rate. Nothing like taking a natural ice bath after every run. The thing I miss most about colleges is taking ice baths.
Trail/grass runs being in walking, biking or warmup jog distance from my house. I feel guilty driving somewhere to run, but it's hard to get a good workout in when you're always either on concrete or worried about being hit by a car.
natural stream to use as an ice bath after long tough sessions, to aid recovery and avoid injury- Better than jumping into a plastic bin/tub full of ice/water.