I have just realised what it is to relax whilst running. I changed the music on my mp3 to Bon Jovi. I was so lost in the music that I didn't realise how far I could run in a dreamworld!
I think its a really personal thing, I couldn't possibly listen to trance as it would give me a headache but I'm sure there are many people out there who couldn't even listen to Bon Jovi let alone run with it! (mind you I really don't think that sort of person exsists when it comes to Bon Jovi

)
Good luck with the music hunt.