Delhi - Amristar - Dharamsala - Manali - Shimla - Rishikesh - delhi
It's a great route, and as above, no problems w/ 4 weeks, that's easy. July is early in monsoon season, but even so pay attention to the news in Himachal Pradesh state. If heavy rain occurs, it's possible to have road closures if there's a mudslide. Big problem with that in Manali last year.
