Paint it a darker color to not show dirt/wear and tear.

Good luck:)

What a fabulous opportunity to create something truly unique and visual interesting! First and foremost, I would not use an opaque cement paint but rather select a from the arrray of beautiful concrete stain colors (you'll like the look and wear over time much better). As for a pattern.. I would select either a diamond pattern on the vertical, a flagstone pattern or my personal favorite; would be to duplicate a beautiful rug pattern in colors of your choice and apply to both sides of your porches. I can also see a great pair of painted rockers on each side of your porch too! Have fun with this!