Finally got rid of the yucky worn-out carpet on the stairs. Instead of painting or staining the tread surfaces, I sanded, filled in holes, primed with a high quality primer, and used luxury vinyl flooring planks on the top of the treads, and finished the fronts with pewter stair nose. The risers and skirt boards were sanded, primed, and painted with 2 coats of semi gloss paint. Below the front edges of treads and where the treads meet the risers and skirt boards, added a finishing touch with some trim. This project was time consuming and I had sore muscles all over from crawling up and down those steps, but I think the finished result was worth it. They look much nicer, and we can get dust and dog hair off of the steps with just a Swiffer. Plus, it only cost about $200 to do 2 sets of stairs (6 steps up and 6 steps down).
So, why didn't I stain or paint the tread surfaces? I originally planned to, and did a lot of reading and research on what to use. But, I was worried about slipping on the stairs. Mom (who lives with us) isn't as mobile as she used to be due to a hip replacement and arthritis, and I was worried about her slipping on the smooth tread surfaces. Even if I'd used slip resistant paint, I was still worried about her foot slipping off the round bullnose at the front of the tread (that's happened to me with the carpeted stairs). The vinyl planks have a textured surface. We have these on several of our floors throughout the house and they aren't slippery for her feet. The stair nose has ridges and also is a bit squared, so it doesn't allow your foot to slip off of the front edge.
I know this is non-standard from what most people would expect to see on stairs, and we'll surely have to change it if we ever sell our house, but in the month we've had this project complete, so far it has been great.