You asked if I went to Gothenburg, and I don't know if you saw my reply.
My wife and I enjoyed the visit to Gothenburg in May, had a wander round parts of the city centre then headed out to The Botanical Gardens. Plenty of insect eating plants on display in the green houses, and a good of collection Allium in flower. Was impressed by what we saw, and would have liked more time to wander round the site, but had to be realistic re connection to bus back to the boat. It was a cool day, but dry.
Would have liked to have visited the Volvo Museum, a short walk from the gangway. About 10 days later the boat stopped in Stockholm. My choice was the Vasa Museum, but could have spent all of my time ashore looking round, but had to compromise and meet up with my wife to explore the area near The Palace and Parliament. The passage back to sea was awe inspiring, so many inlets, islets, must have taken about 4 hours.