Short Stories - Very Useful!

http://www.statemaster.com/encyclopedia/Short-story

Look at these to structure the opening of your film if you need to. That way it keeps you all professional - nobody's idea is necessarily the dominant one thues saving arguement.

Choose a story then consider how narrative structures such as Todorov's, binary opposites, and enigma codes/ narrative arcs would work in the entire plot. This will help you to decide on where abouts in the story to open your film as well as the prominence (importance) given to various aspects of the opening - ie what you need to establish for the audience.
You as a group just need to decide how.