Mumbai
Agra
Jaipur
Bangalore
Goa
Kerela

there are 7 - 14 day rail tours that I've seen, but they never quote prices until you book... so it's difficult to decide.

If I could do a two good tours that will cover different sights and cities, then I'm sure the 40 days will fly bye quickly!!!

I know that I will never have enough time to see all of India... Maybe next time I will do the Himalayas, Nepal, Bangladesh and the Eastern Half of India....