The following lighting setups are significantly more 'brooding' than my previous renders, and in all honesty, I'd sort of tried to keep away from this approach, as I felt it appeared as if I would be making things deliberately darker in an attempt to squeeze a little more drama out of the scene. After the interesting accident with Maya yesterday, my opinion regarding a darker scene changed, and this led me to try out alternative lighting techniques. These experiments are a pleasant change to what I was striving for initially, and its looking more and more likely I'll be going down this road in order to really push my scene to its limits.
This render is lit by spotlights alone, drawing the attention towards the tables. I really liked how the light played across the seating, so I used this method in the next render.
This render is similar to the render above, although the spotlights have been dimmed significantly on all but one table, to draw more attention to the birthday setup at the back of the scene (which I have also decided to bring forward a table, simply to create a balance between the diner environment and the props). I also brought more of the colour out of the scene by placing an ambient light high up in the ceiling. Whilst it doesn't light the scene significantly, it brings out the areas of diner which would not be lit by the spotlights alone.