New Butler's stairs for our Butler!

So this is the Butler's stairwell off of the back of the kitchen.  It goes all the way to the attic, whereas the front stairwell only goes to the 2nd floor.  We're getting all new treads and risers in this stairwell, from basement to attic.  Very exciting.  Can't Decide whether to paint the wood (Fir) or stain it a rich, dark brown color.  Any suggestions?