I may ride English, but I always listen to country when in the arena. Reba, Jo Dee Messina, Dixie Chicks, Martina McBride (the faster songs), Sugarland...
If I'm going something really fast and intense, I like Pink. I don't know why. It's really fun, upbeat music. (Especially love 'Like a Pill'.)
But, if something especially slow and relaxing (Warm up/Cool down), I love that song by her, 'Glitter in the Air'. Not typical Pink, but I love it.
EDIT: Sorrelhorse, you too?
Ha ha, I didn't even read your post before I posted this.