No matter where you are in the US, if some one is visiting you from India, you have to take them to Niagara Falls. It is a wonder of the world for a reason.
Next to Niagara, people love to see the New York City. They have bus tours that take you through the city. Then there is Empire State building. UN building, 5th Avenue and Time Square are all good. I liked the theater too. A photo shot at the Statue of Liberty is a must. If you have some more time, try the Madame Tussaud's wax museum.