Portable electronic devices may be wirelessly charged while resting on a wireless charging surface of a wireless power transmitting device. The wireless power transmitting device may have an array of coils for transmitting wireless power. The portable electronic devices may have coils for receiving the transmitted wireless power. Magnetic sensors may be used in the portable electronic devices to sense magnetic fields produced by the wireless power transmitting device. The magnetic fields may be produced by permanent magnets, electromagnets that are separated from the coils, or coils in the array of coils. Sensors may also be used in the portable electronic devices and wireless power transmitting device such as sound sensors, light sensors, capacitive sensors, proximity sensors, and other sensors. These sensors may be used in measuring lateral position and orientation for the portable devices so that content may be displayed across multiple portable devices.