Friday Open Thread: Road vs. trail running?

I’ve been a road runner most of my life, running marathons and halfs since I was in my mid-twenties. But recently I’ve begun trying out trail races, while a good friend of mine has taken up running ultra-marathons in wilderness areas like Grand Canyon National Park. It’s showing me how different road and trail running really are, which got me thinking — do you prefer one over the other, and if so, why? And what are your favorite trail events? — Terrell