A few weekends ago I took a workshop with Michael Reardon at the Rose Garden in Oakland. He stressed the notion of creating a simple sketch, and using it to compose the painting before actually painting. Below you can see my pencil sketch. Note that I've elected to eliminate the stone wall on the left side of the staircase.
After talking through it with Michael, he suggested I add that left wall, suggesting that it would lead the eye up to my focal point- the small slivers of light on the stairsteps. Below is my final painting.