End of May/Beginning of June I had the chance to join a friend of mine, who was there for business reasons, for five days in Stockholm. Except one day, the weather was almost ideal: that means cool and windy, but sunny. Under circumstances like this almost any city looks nice, and Stockholm even more. Not coming from too far away (Luxembourg), it was still surprising to have daylight until about 23.00hours, with midsummer only coming the 21st of June.
It is worthwhile to go to the main tourist office. They are well organized with a lot of offers for Stockholm and surroundings.
Overall you can get along with English and German. Especially the young people speak a good English.
There are plenty of maps and tourist information around where you can choose from.
Also Sweden has a long and eventful history. Except that they have been more fortunate in not having a war during the last 200 Years. One should take some time before taking the trip and study the history.