Pitalkhora caves, located north of Ellora is much more older site than Ellora. From a tourism point this is less publicized than the more familiar Ajanta and Ellora, and hence less crowded.
For the religiously inclined, the Grineshwar Temple close to Ellora is an important place of pilgrimage.
Daulatabad on the way to Ellora form Aurangabad has one of the most impressive forts in India.
Khuldabad , some 3km (about 2miles) before you reach Ellora has a number of Mughal era monuments including the tomb of Emperor Aurangazeb. The tropical dry deciduous forest, Gautala Wildlife Sanctuary, is located further north of Ellora.
In short, other than Ajanta and Ellora you can spend many days in Aurangabad and go for day excursions to the attractions in the region.