Best thing to do is to enter search terms in the Houzz search bar and review photos. You can save those that you like in an ideabook and you may end up mixing several ideas to get what you want. Try different terms to filter photos.

I'm manufacturer stainless steel railings and aluminum ralings

Having a window at a staircase is a beautiful thing. You can elevate the design of the staircase and make it a feature. I will suggest you do some Stain glass design n the window. It will add color to your interiors and also make it a feature. Since you have a study area in the center, Stain glass window will be a beautiful piece of art to look at.

It would be wrong to give your staircase the first pick of space. You should lead with your living areas. In case you are interested in hiring an architect, you could email me your requirements.