Originally Posted by
Secondwind
If the problem is "how do we incentivize players to do an optional boss after they personally have already gotten the reward from that optional boss?" one answer is to make it not too far out of the way and pretty quick to do. For example in wrath, I almost never saw a group in Culling of Stratholme refuse to do the blue drake boss. Heck most groups I was in did it only to find out after the fact nobody needed it. Why? Because it was fun beating the timer to be able to do it, it was a short fight, and it was literally 10 yards out of the way.
But for an alternative solution, I think this is a good place where VP coming back would be really useful. Say a dungeon is worth 75VP on completion; but full clearing the dungeon bumps the reward up to 150. Just like players will run a dungeon for valor, they'll go a bit out of their way to clean up extra bosses as long as it isn't making their grind less efficient. Running out of your way to kill an extra 2-3 bosses but getting double valor rewards for doing so? It's basically like getting two dungeons in one, and I think it'd work pretty well.