Personally I hate working with Animations by using strings, so I would suggest using SetUnitAnimationByIndex(Unit, Index). Also I'm not sure what unit you're using but in my opinion this is easier to use to make numerous of the same unit have display different animations too.
Nichilus is right about the usefulness of Queue Animation, but again its with strings which is annoying. You'll ultimately have to do whichever is easier/more useful to you.