If you are finding your raid is melee heavy, chances are youll already have the buffs your speccing for covered by another player. For instance you could have a enh shaman covering the haste and ap, a marks hunter covering the ap, or even another dk covering one of them. Personally Id go with a pure tanking build because while the dps buffs are nice, at the end of the day if your tank is squishy it isnt going to help you out a lot :P