Travel Hints for Sweden (Stockholm)

Hello Swedish Community,
I am going to visit the south of Sweden in a few days. I plan to stay for two weeks and will travel from Kopenhagen to Malmö, Lund, Göteborg, Stockholm and back through Smaland. Do you have any recommendations what I should definetly see, where to stay (camping is also a good choice), which activities I must not miss, and where to go out for a drink in the cities?
Your help is highly appreciated.
Kind regards,
Kai