most of the time, after a workout, i listen to either classical, or soft rock, so i can calm down a little. during my workout, i listen to more aggressive (yet not hate music) rock, techno, and some hip hop. i agree with you on balancing it, if you listen to the same stuff over a period of time, it gets worn out, plus your mood stops changing, you're either aggressive, or depressed, or happy, etc. who wants to be in just one state of mind all the time? there is a time and a place for aggressiveness and anger. i've found that on some occasions, i can fight smarter when i'm angry, as long as i don't over do it. I've had moments i get so angry, i can't see straight and just start swinging. but i've gotten better at controlling it, i do think it has a lot to do with the music you listen to. also, change days as far as music. if you're feeling shitty, and don't want to work, listen to the aggressive stuff, see if it cant help get you a little bit more energetic. if you're feeling over-amped, listen to soothing stuff to slow down the thoughts, keep them from racing everywhere.

"war" and "training montauge" by vince dicolla on the rocky soundtrack are also very good instrumental pieces. but then again, most rocky songs are excellent to train to, no matter what the mood.