Help! Making Plans for a few weeks time! - Rajasthan/Kerala/Goa

Hi,

I want to travel for about 3 weeks starting October 25th (less than 3 weeks time :S) Is this realistic if I start planning now?
The only other option would be over christmas and new year - would this be any better? would it be a lot more expensive? I would prefer october if possible.

Could anyone help me with an itinerary please? My husband is flying into Delhi and I am in Pune at the moment, so I can fly to meet him or vice versa (his time in India is limited to 3 weeks not mine)

Taj Mahal is a definite. We are also interested in Rajasthan, Kerala, Goa - but realise this is a lot to fit in to 3 weeks??!
Please advise on different options. Our budget is maybe around 1000/1500 (pounds) for both of us.

Prompt and helpful replies would be very much appreciated!!!