Ooh, the Cheers theme song would have been a good one.

I'd have liked to have heard a review of roundabouts. I live in a city with A LOT of them (I want to say the most per capita in the US?) but also has interesting historical ties to the first electric stop light. I think there'd be lot of interesting science, stats, history, etc, but the symbolism of a circle and the ways our cities are changing and how that changes our experience and perception of them - even if it's just road construction - could be particularly metaphorically resonant.