I've looked all over and can't seem to figure out how to play back animations in nifscope. Can anyhow tell me how to do this? I just want to view various animations to see if any are appropriate for what I want to do.

Easily.
Just open skeleton.nif file then use Spells -> Animation -> Attach .kf from the menu, choose your animation and press the play button ;]

If you want to look at something different than skeleton itself you can copy NiTriShape/Strips branches with body meshes, clothes and armors from other nifs on top of it.