I have just spend 3 months at the Sivananda Ashram in Madurai and without hesitation i can tell that I have had an amazing time. If you are interested in yoga and spirituality while traveling to India then I can highly recommend this place. The people is very friendly, the place is peaceful and beautiful and the food is great but do remember that it is an ashram and there are some rules that you need to follow like no drinking or smoking, lights off at 10pm, wake up bell at 5.30 am and a lot more.
They offer different intense yoga trainings but also a yoga vacation program for those who just want to have a relaxes stay at the ashram while practicing yoga.
I wrote a lot more about it on my blog and added pictures and videos which you can find in the following link http://path2yoga.blogspot.com/