I wish to visit shimla, kullu, manali, rothng pass along with my family, my brothers and their families ( totally 7 adults, 3 kids of 5 yrs or less)in 1st week of May. Is it the right time to visit? Will rathang pass be open then? How many days would it take to have decent coverage of these places if I begin the trip from chandigarh and get back there? 5 days or will it require more ?