How would you feel about a wide runner? You can get padding (I think? I really don't know much about rugs) to make it softer and a litte more plush. Our back stairs are painted white with a Oriental-style runner going down it and I LOVE the look. Ours is pretty cheap carpet (I think it's that cut-to-length stuff from Lowes/HD) and was here from the previous owners, but I think when I get the money to rip it out, I'll do a similar style. And I feel better about my kids going up and down than having just the wood.

Anyway, may not have been the answer you're looking for--I don't really know what kind of carpeting is period for a 20's home other than a runner or nothing. I'd be curious to see as well!

:)
Sarah from Albany, NY