I'm always looking for a great writing contest. A suggestive, but wide-open prompt such as the ones you cite would be great starters for a story. I write stories, and post them sometimes, but unless they are part of an organized contest, they can get overlooked pretty easily. While the joy of writing is a reward, getting an audience does boost morale.
Please do run this contest. I will be an eager participant.
Also, I'm an active Twitter user and have been promoting Steemit there for a while now. I'm not sure it helps, but I try. Also, on my website. You never know....