As a high school student, one of my favorite places to explore was the costume and prop room behind the stage. Everything I could ever imagine and more was contained in that room. There were costumes for kings and queens, every kind of hat you could imagine, practically a whole armoury, and hundreds of other odds and ends that one couldn't even guess what they had originally be used for.
Although the room was not immense, anything was possible. The room contained the potential to put on any story you could imagine; and imagination was the key. All you would need was a sword and you became Hamlet. Add a cloak and suddenly you are Count Dracula. Put on the dinosaur costume and... well you can see what I am getting at.
This was highly influential on how I think about theatre. It is that spark of imagination that I believe to be essential to the creative process. Theatre is all about extending the invitation to the audience to enter into the charade with you - they will only be taken as far as their imagination will let them.
Any play should be feasibly created with whatever you have on hand. If a stick needs to become a sword and a banana becomes a gun, then as long as that "rule" doesn't change and all the artists agree on that, there should be no problem with the illusion. One of my artistic director friends lovingly referred to a version of this idea as "Junkyard Theatre" meaning creating a show out of the junk you have accumulated (theatres generally accumulate lots of junk).
Think of plays that are written to fall into this mold: Our Country's Good, Man of LaMancha, Godspell, and Calarco's Shakespeare's R&J. Shakespeare fits into this because the language will fill in the gaps that realism doesn't cover. Mary Zimmerman's plays rely heavily on imagination and imagery. What other plays or playwrights seem to fit into this idea?