We have wooden stairs, and 5 dc aged 2 up. No one has ever slipped on them. The stained steps and painted risers would be perfect. You can buy a stain with a varnish included in it, that's what dh painted ours with, although they were new stairs
I hope it's obvious, but don't paint your stairs with gloss paint. My cousin lived in a house where the landlord had done this, it's illegal for landlords to paint the stairs with gloss apparently because it makes them slippy, and she slipped and broke her coccyx (sp?).
Personally I wouldn't paint the stairs as anyone rushing up or down, for the phone, loo, front door etc will sound like a heard of rhinos.
We're painting the uprights of the stairs white and just sanding back and varnishing the treads. Hopefully that will be easy to keep clean (the old stair carpet is filthy even after proper cleaning) and won't mark. Our builder said that even specialised floor paint scratches quite quickly and recommended just going with 3 coats of polyurethane varnish.
We got DS some of those cat-paw sock/slipper things with grippy soles for walking around, could those work?
We have renovated downstairs - and have run out of cash to replace carpet on stairs/landing (which is grim - and my two year old has just carefully rubbed a bottle of shampoo into it!!) The floor boards are in quite good condition - but have been stained dark. Was thinking of just removing carpet and painting them. Has anyone done this themselves? Expensive/difficult/can I do it myself??? Also do the stairs become slippy for toddlers to negotiate?