The Himalayas are a diverse region that spans a wide breadth of north and east India. It would really take it's own 2 week trip to appreciate it from either the north or the east perspective (rather different experiences IMHO). If it is your first time to India, I would recommend staying Inland and not venturing too quickly into the thinner air before you've gotten settled in. Also, I would not recommend any Himalaya trip by yourself. At the very least, you should travel as part of a group w/ an experienced guide, but ideally you would bring your own group