When I go on trail rides, a lot of the places have dirt roads for the trails. On the straight part I really like to open Sassy up, she never gets to go fast and it helps me build confidence while I am on her. And it's fun. Sassy never acts like she is going to blow up after it, she's just a little more awake and wants to carry on at a nice trot.
There was one field I was able to let Rosie open up in, it was just sold short grass, no holes sticks nothing. It was awesome!
Nothing like having a 21 year old out shine the younger horses;)