If you had four nights on your journey between Stockholm and Copenhagen and wanted to see both Gotland and Glass Country, would you do 3 nights in Visby and 1 in Kalmar? Or 2 in each? Or something else? We have family heritage in Visby so want to be there a decent amount of time, but also very interested in the glass country near Vaxjo. Also, we will be renting a car, wondering if we need a car while on Gotland, or should we rent after that portion (when we get to Kalmar). Any thoughts appreciated!
I spent 30+ hours in Visby a few years ago, with just one hotel night. I was able to walk essentially every medieval street in Visby in that time. I'd have needed more time to see other parts of Gotland, which I'd have liked to do--but I wasn't going to rent a car. I think your answer depends on whether you're willing to take the car over to Gotland (does your rental company allow that?).
Kalmar is a pleasant and attractive place, and there's the castle, which can definitely occupy some time. But I'm more an art-museum person than a castle person and found Kalmar a bit underwhelming compared to Goteborg and some other places in Sweden; YMMV on that score. I'm unclear on why Rick highlights Kalmar; I guess I need to reread the guidebook!
Loving glass but not having a car, my exploration of glass country was limited to Vaxjo. The museum there is good, though not huge. I enjoyed the neighboring emigration museum as well. Incidentally, Vaxjo is pronounced more or less as "Veck wa".
I visited Visby without a car and visited Kalmar, the glass region, and Öland with a car.
For Visby itself, you can get by without a car. If you want to explore Gotland beyond Visby then a car would be useful. In the summer, Visby accommodations are hard to come by if you don’t book early.
Kalmar itself doesn’t take much time but if you are visiting the glass factories and/or exploring Öland (which has some interesting sights), you will want more than a day.
For Gotland, we were just doing bus and rental bike for our four night stay a couple of years ago. So you might consider to check if either option or a combination suffices for you.