While if you are not the typical stereotype that heat will affect you (while sometimes it does ) but if you can overcome it, any time is a vacation time.
India can be visited for any of your following needs :
Materialistic things : Business ( Due do world turning towards India as the next big thing).
Pure Holiday : Deserts, Seas , Rivers, Beaches , Mountains , Snow , Sun, Adventure.
Spiritualistic : For the most Peaceful places outside and inside yourself . Which
can be that no other country can offer.
Culture : The only country with so many rich and diversified cultures.
Old World : Lots and Lots of Historic Monuments .
Religion : Hindus, Christians, Muslims, Sikhs, Jain's, Buddhist, Zoroastrians and Jews.
Feeling Lonely ? : I Feel This is the place for you to be.
Low Cost Medication : With The most Dedicated Hospitals,Dedicated Doctors,Modern Technology and best of all the low cost medication . ( It is now the becoming the medical hub of the world).
Job Outsourcing : The Back office of the World.
Food : Feeling Hungry ? Indian Food available Every where for country specific it is mostly the cities.
Bollywood :
Romance : Quiet a Lot of places for your ....
Alternative Healing : Ayurveda , Yoga, Sidda
Some Tips :
1. India is crowded at places, i wish you like people, after all we are human beings. And being crowded is not that bad. It is just that you need to get used to it.
2. Don't feel superior or inferior from the places you are coming from. It actually ruins the enjoyment which is actually there.
3. Just be prepared for some initial changes in your body which you will get over .
4. Some places are with less arrangements.

Will be continued ....