I like @kelly's idea of picking a lovely fresh color of paint for the door. You can then bring it down onto the stair risers. Either a solid color to match the front door, or go wild and add some decorative elements to the risers with stencils. Or think of staining the door a great color and coordinate the stair railings and risers. I have an idea book put together for just such project that might spark some ideas for you. http://www.houzz.com/ideabooks/16700983/thumbs/Kathryn-Delany-s-Decorative-Stair-Risers

Thanks charleee, sorry no better photos as house is in another city, I haven't even set foot inside it yet. I am trusting my husband on this one! Our youngest is 5. Thanks Sheilaskb for the strip suggestion and the advice on the carpet. The kids are really good when we go out, holding onto rails etc but it is another story once we are home. I guess I will need to be a little more vigilant once we move in.

These spaces can look awkward but yours is quite inviting with those windows. It could become a retreat space, that allows someone to be near the action without being in it. Seating or lounging would work with the very low head height. I could imagine it would be a great spot for a couple of cool beanbag seats, a small funky bookshelf and a sleek retro lamp, or if you have children to cater for a games setup with storage in a retro ottoman.

I suspect your best course of action would be to contact a local engineer and/or builder -- without knowing what area you are in , and local rules and regulations , any advice wouldn't be much value from us , and quite possibly won't meet compliance .