Copenhagen in May + where else

Stockholm is easy to combine with Copenhagen if you want another city destination.

I went on a Baltic Cruise in 2019 and really liked Helsinki and Tallinn . I was not expecting to like both cities as much as I did.

However being on a cruise, I was only in each city a few hours.

Aarhus:

One train from Copenhagen all the way!

https://www.dengamleby.dk/en/: open air museum with buildings from different periods, shops and restaurants.

https://www.aros.dk/en/: paintings, sculptures, etc.

https://shop.kattegatcentret.dk/en/: fish and other sealife. Citytrain most of the way. Bus for the rest.

Nice eating environment on Åboulevarden (No 38 would be a good place to start), next to the stream going through Aarhus. But also visit the street food market: https://aarhusstreetfood.com/en/

Oslo:

Go by ferry from Copenhagen: https://www.dfds.com/en. Leave Copenhagen around 15:00 and arrive in Oslo next morning.

https://en.wikipedia.org/wiki/Frogner_Park: dedicated to sculptures by Gustav Wigeland.

https://www.visitoslo.com/en/activities-and-attractions/boroughs/holmenkollen/: No snow in May, so you can study the ski jump and the ski museum without rush. The area around Holmenkollen is a skiers paradise in winter and a hikers paradise in May and all summer.

https://www.vikingtidsmuseet.no/english/

https://frammuseum.no/

World War 2 museum

Thanks for the ideas. Ferry to Oslo sounds like a good plan.
Questions:
1. Oslo or Stockholm as the add on city?
2. If Oslo (or Stockholm), how many days in Copenhagen vs the other city?

1. It depends on what you're looking for. While Oslo is lovely in many ways, Stockholm wins in my opinion if it's a choice between the two.
2. If you choose Stockholm I'd recommend an equal split between the two.

While Oslo and Stockholm are both very much worth visiting, I agree with Badger that Stockholm should be the top priority (unless there are logistical or family-heritage reasons for favoring Oslo). In addition, Sweden is likely to be somewhat less expensive than Norway, which most people would not object to.

If you want to combine the city of Copenhagen with a few days of gorgeous rural scenery, that might argue for Norway's fjord country.

I'm considering visiting Copenhagen in the next couple of years for roughly the same amount of days as you. I was thinking of combining it with a few daytrips in the area. My initial thinking (and I've only just started looking into it) is to visit places like Malmö, Roskilde, and Hillerød as daytrips from Copenhagen.

While there certainly are things to see and do in Malmö, it would not be on the top of my list of places to visit in Sweden from Copenhagen. For a day trip, Lund, Ystad or Helsingborg has more to offer in my opinion. You can also consider Simrishamn or Ven.

Thanks, Badger. I don't want to overtake the OP's thread, but I've made note of your suggestions.

I'd recommend Stockholm. It has everything, is beautiful that time of year particularly before most tourists, is very outdoorsy in culture (well Sweden is in general, IMO), beautiful walks, day trips and/or the archipelago. Of course, Stockholm would be my first pick of any Scandinavian country, but that's just me.