Charles, my father's side of the family is from Sweden and I've been there a couple of times.
Last time I went, my sister, wife and I spent a few days in Copenhagen, then took a ferry to Malmo, Sweden. Sweden has a great train system which we took to Gothenborg for a couple of days, then to Stockholm for a couple of days.
Both cities are beautiful and the people are great.
My dad took a Canal / Lock trip from Goteborg to Stockholm once, which he enjoyed immensely but said that someone younger might find a bit slow unless they were with a spouse or S.O. and would enjoy the relaxed pace of travel.