Closer to home (53,250 LY from me atm), Uranus's moon Ariel has some pretty amazing misty canyons:
http://youtu.be/0aelxiA2WeQ
Yeh, popped to that over the weekend, but again the ravines/valleys tended to be quite wide so not great for flying thought etc... Maybe the engine just doesn't create smaller ravines that offer a low flying challenge!?