IMO the best source of poeetics is from the things you want more than just poetics from, say a dungeon that contains a minion you want. If you're of the mind to grind it out, maybe level a class while you do it, so long as its a level cap dungeon the poetics will come naturally as you run for levels/minions/glamour. Same to 24 man raids and so on, I find it helps immensely to have a side motive aside from just grinding for poetics.