You can either base Aurangabad or Jalgaon for tour to Ajanta and Ellora. You may find direct flights for Aurangabad from Mumbai or Train to Jalgaon/ Aurangabad. Train journey takes around 7hrs and you can later hire a taxi to visit Ajanta and Ellora caves.
Ideally a day each cave is desired as both are at geographically different locations and both have early evening 5.30pm as closure time.