Rishikesh India is the yoga capital of the world.
Dipping your feet in the Ganges while setting a flower bed afloat is part of the tradition -- as is full bathing, for those who want a more authentic experience. The river runs rapidly, however, and the banks can be slippery with moss, so do exercise caution.
A day trip to the charming neighboring city Haridwar is worthwhile to contrast its aarti, which is less catered to western visitors. Be wary of false holy men looking to fleece you for a "donation," however.