Without knowing anything else about the space, the bottom left cream sample seems to work the best.

The house is transitional, blending cream tones with blue/gray. Staircase walls are more beige, foyer fixture is black wrought iron, floors in foyer are a shade darker in walnut.

Another view with light fixture

Given that the stairs curve, I feel a geometric is not the best choice....the curve will "add" to the pattern and it may look cluttered and awkward, or even dizzying. I'd recommend a solid color, or perhaps a very small pattern or organic design, such that it's not so obvious that the pattern is in effect distorted by being placed in a curved layout.

Safety is also a factor....a flat, yet textured carpet would seem to be preferable. It is essential the carpet be very well anchored. Patterns can make it harder to judge depth.

http://whimsicalhomeandgarden.com/making-stairs-safe/

http://www.cmhc-schl.gc.ca/en/co/acho/acho_012.cfm

http://www.human.cornell.edu/dea/outreach/upload/Stair-Safety-2-2.pdf

http://www.amazon.com/Treads-Collection-Indoor-Resistant-Carpet/dp/B00W4D15U0/ref=zg_bs_110761011_7

http://www.livingmadeeasy.org.uk/scenario.php?csid=79

My first question is traffic. Kids? If so one of the greys, if not cream.

Without knowing what other colors flow into and out of the foyer area, I think it depends on whether you want to call attention to the staircase or have it blend in. I actually like the top left sample for contrast, however, the middle sample would merge the darker wood on the lower flooring with the lighter wood on stairway creating a more blended look. Also, need to consider where the stairs merge on the upper floor.

HI -- What you are not thinking about is how a pattern is going to work on curved stairs . A runner with more of a textured blend of colors might be the better choice for stairs . Putting a gridded pattern is not going to work on your stairs . You also have to see how the rugs texture will look when it is folded around the edges of the steps . If you bend the rug material and you can see down to the backing , then it will not be good and will wear too fast . Get some better advice from a good carpet store . Stairs need special treatment to look right and last well.

The middle one that says Kane on the sample, it is more sophisticated. The other's are seen everywhere and do not blend as well with the stairs.