An electronic device may include control circuitry, sensors, and wireless circuitry having antennas. The sensors may generate sensor data that is used by the control circuitry to identify an operating environment for the device. The sensor data may include a grip map generated by a touch-sensitive display, infrared facial recognition image signals or other image signals, an angle of arrival of sound received by a set of microphones, impedance data from an impedance sensor, and any other desired sensor data. The control circuitry may use the sensor data, radio-frequency spatial ranging data, information about whether audio is being played over an ear speaker, and/or information about communications protocols in use to identify the operating environment. The control circuitry may adjust antenna settings for the wireless circuitry based on the identified operating environment to ensure that the antennas operate with satisfactory antenna efficiency regardless of operating conditions.