The nearest airport is Aurangabad and not Bombay, Ellora is 29 kms from Auranagabad and Ajanta is 120 kms away from Aurangabad.
Wonderfull place but I suggest that both be given equal time by visiting Ellora on one day and Ajanta on one day. There are many buses from Mumbai and other places. Plus there are 2 direct trains from Mumbai and one direct train from Delhi.
There are two flights in a day to Bombay and one to Delhi. There are a host of 5 star hotels and three star too.a place worth visiting , in the month of December and Jan.