Two short stools close by each other can be a bench in a park, or a roof ridge atop a house. A single high stool can be a throne room. A high stool with a short stool next to it can be a tree to climb, or a mountain. Then you position those locations on your stage in whatever arrangement works and looks best. Look for ease of reader movement, stage balance, and openness to the audience.
Readers can move to different stage areas for different scenes.
Don't forget the narrators. Drawing a series of movement diagrams can help you spot problems, save time during rehearsal, and jog your memory the next time you use the script. In one simple diagram system, circles are low stools, double circles are high stools, crosses are readers, and arrows show movement. This indicates to the audience that the reader is out of the picture. If sitting on a stool, the reader can usually just turn around on it.