I decided against the stained glass approach in the end. I Chose instead, to focus on repeated patterns— a race horse silhouette, with the silks in the spotlight, and a larger repeating pattern behind them.
After much experimentation with various backdrops and shifts in color for the silhouettes, I landed on a maximum vintage palette and pattern, which incidentally called for my current favorite typeface. 🙂
Below: a couple of the numerous rejected schemes