Depends purely on what you want to see.. Rajasthan is lovely at the time you are planning your trip and it offers deserts, palaces, history and tradition. Other places of interest would be Goa which offers great beaches, resorts and lovely waters. Then there are other places which offer lot of architecture and history if that interests you, so based on that one can plan the India trip accordingly. For Nepal, typically 7-10 days is what people opt for, but again depends on your preferences.

You have less than two weeks on the ground it sounds like. With that amount of time, spend all of it in India. Dividing the time between two places will, IMO, give you less rather than more.

Rajasthan is where most people choose for a first trip to India. But India is a big country with lots to see and do. So do some reading and see what appeals to you.

Nepal is fascinating and you could easily spend all of your time there. I think you need a week just for the Kathmandu Valley. With the additional time you have you could go to Pokara as well.

we found 5 days perfect for kathmandu and surrounds... generally it is quite expensive to fly there.

you might be happier to just stay in india and do the golden triangle (delhi, agra, jaipur and maybe udaipur).

we loved using castle and king in delhi to help with planning and to get a good driver and an occasional guide..

It depends on you. India is beautiful in any weather, climate. And these October, November, December months are good to enjoy the winters of India. Its good to visit Rajasthan in Winters. Its the right time to enjoy Rajasthan.like: Jodhpur, Jaisalmer, Bikaner, Barmer etc. These all places looks very fantastic in Winters.

Hi
Visiting India in November/December, you can expect great weather. In a week's time, you can do the golden triangle tour Delhi-Agra-Jaipur and visit Ranthambore National Park. Suggested itinerary :
- Delhi - 2N
- Agra - 1N
- Jaipur - 2N (if you can add additional night, visit Chowki dhani)
- Ranthambore - 2N
- Delhi

Being peak tourist season, it is recommended that you book hotels well in advance.

You didn't ask, but be sure to bring mosquito repellant. The malaria ones bite at dusk and dawn and the Dengue fever ones bite during the date. Not all mosquito bites transmit illness, but it's important to reduce the number of overall bites. October and November will have an increase in mosquitoes since it is post monsoon.

i would skip ranthambore and add a night to agra so you have a full day there and one to jaipur too