I'd surely recommend visiting the backwaters of Kerala(known as The God's own country).Then the country's capital - Delhi, home to a lot of historical monuments. Then to Agra, the home to the Taj Mahal- one of the wonders of the world, which is just a few hours ride from Delhi. If you travel further North , you could go to Ladakh and Leh- beautiful sceneries await. And wherever you go , make sure you try out the local dishes .I'm sure you'd be impressed by the number of different types of food you get across the country. Apart from the monuments there are a lot of temples you could visit and you'd be struck by awe on seeing how collosal a few of them are. Overall I'm sure you'd enjoy your vacation.