I didn't do rafting but I did continue up to Gangotri and then myself and a friend hiked to Gaumukh which was a phenomenal journey all on it's own. I also spent several days in Dehradun, Mussoorie , Dhanolti, and Almora. Many other places as well but those are the ones I recall from your area. I Went as far north as Nubra Valley and as far south as Goa, mostly Arambol