Also - note that the specific look of the virtual set as shown in whatever thumbnails the client has found would come from lights, textures, and render settings/passes created in Maya or Max -- that could be difficult/impossible to translate through to After Effects.
You could find a 3D artist who could render passes from matched/tracked cameras that you would then bring into After Effects to add reflections/shadows of the talent into the set you render from 3D. I wouldn't expect to just pick up Maya or a 3D package quickly if you haven't used one before, though, so budget for a 3D artist.
Perhaps you shoot with locked off cameras and create a preset collection of stills of the environment to composite the talent into? The 3D artist just creates some preset views and you don't shoot any moving cameras that would need to be tracked. Plan it out, know that you have various set different angles you can shoot from, and try not to show contact with the floor, which makes it trickier.
Steve's Tricaster idea sounds solid, though, if the quality is up to par with what they're looking for. (Haven't used one before myself.) Especially for a series of multiple videos. Then you see just what you're going to get on-set, make adjustments as needed on the fly, client approves then and there, and you don't get into endless hours of post time tracking cameras, long 3D renders, and comping green screen shots.
Just some general thoughts!
- Nathan