As I see the playwright as more of an auteur who should have the characters, dialog and stories at fingertips, ready to use to illustrate whatever worlds the writer chooses to create..
I've always used Film for inspiration for theatre (as a means of absorbing quality unpredictable plots, as well as soaking up great ways to tell complex concepts simply in dialog) - try deliberately watching some good quality films..
Kind of the equivalent of hunting for high quality mince to drop into the sausage machine, so that when the time comes to make sausages, your own that emerge are unique and of a quality above the average
So that hunting for 'raw mince' needs to be a constant thing, otherwise average every day life, and a diet of predictable stories (which is what a lot of US film/theatre is) - just isn't going to kickstart the creative engine thoroughly..
I'd recommend hunting down some titles from the Korean cinema - as for quite a long time now, they've seemed to be at the cutting edge of utterly genre-blurring storylines and totally unpredictable stories, with a serious level of expertise in acting/technical..
Titles like Old Boy, Bad Guy, Samaritan Girl, Bungee Jumping Of Their Own, Joint Security Area, Save the Green Planet.. are a good start point..
Or for direct theatre:
Dig out masterpieces, like the Royal Shakespeare Company's filmed version (8.5 hrs!) of 'Life and Times of Nicholas Nickleby' - or soak up Peter Brook's gigantic version of 'The Mahabharata'..
or for a glimpse of what is possible in theatre - from a visual/set perspective, try hunt down source material on Robert Wilson, whose avant garde theatre works are pretty awe-inspiring in terms of creating visual theatre 'moments' - using a variety of theatrical forms and tools, from lighting, through to multiple layers of action and business on a stage by characters..
/my two cents worth