During the summer Trädgården is the place to be if your out clubbing. It has a great festival atmosphere. The chance of you getting seperated from your friends is immidiate but you will meet new ones. I have a love-hate relationship with this place, watch out for the massive que and the ill willing pointers.
This is a great spot for lunch or coffee! In the summer you can sit outside. They have a beautiful botanical garden and is located next to Brunnsviken (lake). The also have a huge greenhouse with plants from allover the world.