Brian, yes, that "rounded" nose makes it a bit tougher to do with quarter round. Here's an idea, kinda "artsy" but something I think could look really sharp in the right surroundings. What about giving the stairs an upholstered look?
You can get 1/2" or 3/4" cotton decorative rope (like used for drapery tiebacks) in all kinds of colors, and it's sometimes used for just this type of thing, too. This can be glued and tacked along the stair sides in a continuous rope. I could see this really setting off finished wood steps against papered or painted walls.
This may not be "right" for you and your home, but I thought I'd throw it in as an idea.