The Caves of Aurangabad by Carmel Berkson (1986) — A detailed art-historical study of the Buddhist cave sculptures at Aurangabad, with close attention to individual panels and their iconography. Dry in places, but invaluable if you want to understand what you are actually looking at in the caves. Berkson spent years working on the site and brings genuine scholarship and enthusiasm.
A History of South Asia by Burton Stein — For readers who want to understand the Deccan's place in Indian history, Stein's survey provides the essential framework: the Mughal expansion into the Deccan, Aurangzeb's long southern campaign, and the eventual collapse of the empire. The chapters on the 17th and 18th centuries illuminate exactly the period when Aurangabad was at its most important.
The Mughals of India by Harbans Mukhia — A compact, elegant introduction to the Mughal dynasty from Babur to Aurangzeb. Mukhia is particularly good on Aurangzeb's complex legacy — the last great Mughal was both the most powerful and the most destabilising of the emperors, and the city of Aurangabad is essentially his monument. Readable in a single long day and ideal preparation for a visit.
Travels in India by Jean-Baptiste Tavernier (1676, translated) — The French gem-trader Tavernier crossed the Deccan several times during Aurangzeb's reign and left vivid, detailed accounts of the cities, courts, and roads of 17th-century India. His description of the Deccan during the height of Mughal power is as close as you can get to a contemporary witness of the world that built Aurangabad.