At work, we've been up to creating a technical demonstration that features an architectural walk-through in an hotel lobby.
Our start point has been VRay renderings done with the model, to setup the ambience. We then worked with RTGU pipeline to export from 3dsmax, and reproduce the lighting.
The biggest challenge was reflections, that are present a little bit everywhere. I tried to approximate the glossy reflections using a volumetric texture storing spherical harmonics. We managed to tune something that's close enough, but reflections are tough beasts. Nest time, gotta try something mixing screen-space techniques maybe.
Another problem we faced was storing the HDR lighting in our lightmap system. The memory budget went up pretty quickly, so we could not afford as many details as we'd have liked. To improve to overall looks of lightmaps, especially in high-contrast zones, we're using Point-disk sampling to upsample the textures - it looks far better than bilinear filtering.
Some more information, and a demo download link, are available here.
Of course, and as always, any feedback is welcome !