Don't be afraid to adjust the gamma or exposure of the environment node. Dropping the gamma slightly can yield intensely dramatic, high-contrast shadows.
To get the absolute best out of your , consider these quick tips during your production workflow: light preset.hdr
Like most uncompressed .hdr files, high-resolution versions of these presets can chew through your GPU memory during render time. A lightened .exr or lower-res version for background calculations would be a welcome inclusion. Don't be afraid to adjust the gamma or