shots 2-4 look absolutely fine, although like necros suggested, spotlights would work a treat on those flat beige walls
with shot 1, i'm not really a fan of the top of the building being completely level. height variation is a good thing.. although since i can't put into words exactly what i'd do i
threw a quick example together in worldcraft, perhaps adding a little light fixture on the top of each one afterwards. i know you said the player only passes through once, but it's still an entrance, and entrances should be at least a little bit pretty ;)