Up to which skill can you train peace by area-peacing?
Btw you area-peace these days by targetting yourself with peacemaking. It could be possible, that you can get only up to GM that way. From what I've heard, you're having 100% success chance on area peace at gm music/gm peace.
Music over GM adds to your succes chance. That way you're having higher succes chances with the other barding skills. (It sounds good but it isnt, if you want to have many gains. Especially at higher skill levels you need to bard onto more dangerous creatures than you would have to with only gm music.)
I dont have exact lists, when to bard which creatures, but an other trick with them. Toy around with different music instruments. Exceptional instruments give 10% more succes on any monster, slayer instruments giving 20%, if used onto the fitting creatures and -10% (or -20%? ... cant remember) if used onto monsters of the opposite slayer group, normal/npc bought instruments are not giving any bonus. Knowing that you can improve your gains on certain monsters/gain for a longer duration on them.
I am not fully up to date with todays barding possibilities. There was a point (or at least I think so), where you could provoke something onto player controlled pets. So ... if your having a guild mate training his/a pet with a shadow elemental, you could try to join in and provoke those two onto each other.