U is for ... Unique

Authors know that they have to write a good story in order to sell. But there also needs to be something unique about their story idea. I've read that there are no new stories, just different (unique) takes on the same one. Take Romeo and Juliet. How many other books have been written with this same or similar storyline? Here are a few that I can think of quickly:

• Twilight
• West Side Story
• Wuthering Heights

What stories can you think of?What do you do to make sure you have a unique story? As a reader, do you care that much if the story is unique, or don't you mind if it's the same story, different characters/setting?