Pink marks the spot. This front view reveals the camera up top and facing toward you at an angle. Yellow circles mark the light sources, the dashed lines the extent of the spotlights. Each spotlight, no matter what its cone looks like, can have its strength, color, and texture modified. Light sources can also be animated, either moving or changing in color and strength.

Tree Room mesh

The thick horizontal line marks the floor plane so you see the bases of the supports are really cubes that extend beneath the floor.
As for the ceiling, you see here it can be a portion of mesh sphere. It can also be a NURBS surface, a curved plane. What governs my choice is effects I want and ease of construction in each specific case. Each type holds advantages for various amounts of deforming, shaping, and for texturing.