A gas turbine engine comprises at least two compressor rotors, including a first lower pressure compressor rotor and a second higher pressure compressor rotor. At least two corresponding air taps include a low tap for tapping low pressure compressor air from a location downstream of a first stage of the lower pressure compressor rotor, and upstream of a first stage of the higher pressure compressor rotor, and a high tap to tap air downstream of the first stage of the higher pressure compressor rotor. an air handling system selectively communicates both the low tap and the high tap to an air use destination. Air is selectively supplied from the low tap to the air handling system at a high power operation and from the high tap to the air handling system at a low power operation.