I see what you mean about grounding the stairway. I can show these pics to her. She also has heart pine in the foyer and on the stair treads. It's right as you come in the front door, so the dirty risers are in your face. Adding something such as a rug wouldn't work, as she can't lose any space on those treads. Originally the stairway was to have a landing and then turn. Supposedly the previous owner/builder enlarged the upstairs bathroom and had to change the stairway. Now it comes straight down. When the kids were younger, my sis would threaten them about running, afraid they would break their necks. I'm happy to report, they're still in one piece:) ah, but those narrow treads!

What is your current risers material made out of now? White is a classic look that I find looks very nice. sometimes oak treads and oak risers can be a bit Too much wood. but that also depends on the surrounding areas, if oak risers would look good with the surrounding materials then go for it. but I agree with Tundra finish works that I wouldn't pay for oak risers and then paint them. Poplar is a nice choice for material to paint. its cuts/sands nicely and accepts paint very well.

Priming won't help hide imperfections, but it will help with adhesion. This is especially important on stair risers because people will be banging their heels against them when they walk down the stairs. Sand, then prime, then apply some patching to the imperfections, sand again, prime the patched areas, then apply two finish coats.

Same color as the trim I guess . Pretty hard to advise with only that little snippet of stairs. Are these the only stairs ?