I recently tried out a new tune for my standing hill climbs -
Metalica - Enter Sandman
Really good easy to follow heavy bass and not a typical shouty song (would appeal to most)
Helped my group to keep to a good rythm and really add some reistance, because the beat is so strong its easy to say turn it up, make them work as hard as the beat.
Got some really good feedback, let me know if you try it and what feedback you get.