Some people live in the same town, in the same house, their entire lives, while most move at least once over the course of their lifetime. Taking into consideration all the places you have lived, which one was your favorite? Why?
Perhaps it was because of the neighbors. They were friendly, open, and welcoming and your best friend lived right next door. Maybe it was that the location offered plenty of things to do, like roller-skating, hiking, swimming or exploring.
Whatever the reason, that place offered you something that no other has.
Your characters will have a favorite place as well. Begin by creating backstory for each of your main characters. Give them each a place and at least one reason. Those places might not appear in your story, but they continue to appear in the memories that your characters carry forward. They may even influence the things your characters say and do.
Your task is to write a story in which a favorite place appears in some way. It could play a prominent role or it could come up in discussion. In this story setting is important, but so are the memories.
Remember that not everyone in a family shares the same opinion about a given place. This could lead to some interesting discussions that create a sense of tension.
Have fun with this one.