Manali shimla kullu are very common places to visit in summer. although they are crowdy enough during summer so i will not suggest you to visit. i will suggest you to visit Sadhupul in himachal. sadhupul is a very peaceful and loving place to visit. you can do riverside camping there. bonfire music..musical night..crystal clear flowing river..trekking make it different from other place. it is quite budgeted place.
Kashmir, Uttrakhand, Himachal pradesh will be the best place to visit with the months of summer
for adventure sports
Rishikesh is best for river rafting