- Backwaters in Kerala is fantastic. Basically you can rent a boat that takes you down the back rivers of the state through rice farming and fishing villages. The boats are like a one room hotel and they cook for you! Its like being Huck Finn in rural India. Definitely one of my favorite parts of all of India
- Thanjavur is perhaps the best ancient temple in Southern India. Its was carved from a single 200 meter rock and has great detail. Plus the city has some of the best bronze work in all of India. I got two great pieces from there. Bargain hard and start at half (at least) of the asking price
- Mysore/Somnathpur. Mysore is a charming city with a great palace, a fanstastic Nandi statue on a hill overlooking the city, and is a short 1 hr bus ride to Somnathpur, my personal favorite temple with the most intricately detailed work of any temple I've seen. Also, if you're into yoga its the birthplace of Ashtanga.
- Hampi. The gem of Southern India, its one of my favorite places in the country. Directly east of Goa (you can take a train or bus) its a series of temple ruins arranged in a number of complexes. The scenery is fantastic. Small hills made of red quartz boulders with rice farming villages in between. Its like farming on Mars. Is she goes tell her to check out the Mango Tree restaurant by the river. Great views and good food.
- Bangalore. I'm not much for this city, it has a few nice parks, churches, temples and decent city amenities. But its close to two great temple ruins - Belur and Halebid. Both are great and a quick journey from Bangalore. Is she's flying in here these are great day trips to make.
- Kodaikanal. A great tea and coffee growing region. If you want to get a flavor for rural India and see natural beauty this is a good start.
- Pondicherry. People forget the French also came to India. The old city is a charming French colonial town that turn of the century. Go to the newer parts to get some masala.
- Mahabalipuram (spelling). A decent beach town close to Chennai/Madras that has some great ruins. Don't expect to go swimming. In fact, stay out of the water. There is a hippy community called Om close by, but I never checked them out.
In my opinion Varkala and Kovalum in Kerala are over rated, but if you want a beach escape I would pick Varkala, the cliffs meet the ocean and make for a great landscape. Also, at the very bottom of Southern India is Kanakumari (spelling) where the Indian Ocean, Bay of Bengal and Arabian Sea meet. I've never been there, but I heard it is good. Also Hyderbad has great museums and food, but I've never been so I can't give any advice.
Southern India is fantastic. I travelled there form 3 months in '02 and again for two weeks in '10. There are more English speaking people, and it doesn't have the hassle and hussle of Northern India, which can overwhelm foreign tourists, especially if its there first time to India. Also there are great arts and crafts, and for women jewelry, scarves, stoles etc. You can buy great gifts for everyone back home. Hope this helps.