As someone who spent many years in the design and fashion business, my taste changes with the fashions.
With a big investment I will try to be a little sensible and go with what my own taste dictates, your hall stairs and landing is a big investment.
I have tried most of the colour schemes and always come back to my own favourite colours. I never tire of gold, beige, cream and a little brown. To jazz up these colours a little wine or red here and there is wonderful for the splash. Keep the splash to replacable pieces, like cushions, decorative additions.
It is easier to paint a few strips, on the current fashion colours, on the walls, at regular intervals. Like 8" plain and then one stripe or two stripes of different fashion colours 3" each with 3" strip between. You can use masking tape for guidance, it works well.
Hang a little weight down wall and put tape on that line.That will give you great variety and fashion while keeping the changes inexpensive to ring.
I have had the red carpets which I loved but they broke my heart keeping looking good. Dont go too dark As every mark will show. A very mild pattern, like in the Ulster designs,make keeping the carpet easy. If you have little marks on the carpet the small pattern will detract the eye from the mark.
If you can afford, it is well worth it, get the scotch guarded type, or get it done for you. It really works. Would second TC Mathews they have wonderful Ulster carpet - you will tire of it before it wears out.
I recently had a friend spill a whole glass of red wine on a cream suite, I hope I succeeded in hiding my panic. I poured a half bottle of white wine over it straight away. I could not believe in the morning no sign of a mark at all. The suite is scotch guarded. It is a bit like a plastic cover on the suite.
Best of luck Browtal