Seeking advice on Health / Yoga Retreats


Hi all, my wife and I are going travelling next year, passing through Thailand and India. We thought we would like to do a couple of retreats, 1 initially to cleanse our bodies to invigorate us for our journey and later a Yoga one.
I have the idea at the moment of doing the health part of it in Thailand and the Yoga part in India. We are planning on Mumbai, Goa, Delhi so far.
Does anyone have an suggestions or advice for places to go or even just good sites on the net to do some research?
Rob - Perth Western Australia.