I have a Warrior who I do nothing but PVE with. My 2 specs I use are prot and fury, I have no problems just staying in Zerker stance when I'm fury because the only time I'll ever really need to use charge is Shade from kara, and the only time I'll need to use Thunderclap is when the a Druid or Pally tank sucks and needs to negate more damage so he con survive, though if that's the case I don't think I would even want to be in that party. For prot though, yeah switching stances is good... but for the most part I'm lazy and I stay in def stance, you have everything you need to be functionable besides a fear break that you only use on select bosses, so in the end it really doesn't matter if you know what you are doing.