sometimes you need to put several parts on the single  upper shield to be interface and display for the product.

screen/leds/digit.-display
switches buttons - activation and interface
light sensors.(or other upper sensors that need to be exposed)

my suggestions
proto-shield that will include little display and place for other parts.
single parts that can be placed on easily on protoshield ,especially leds and switches buttons  and some kind of display(single digit for instance/text screen)