Last christmas me, and my family took a cruise to Denmark, Copenhagen to stay there for a long-weekend. Copenhagen is really beautiful.
We went there in December, and the whole city had a christmas theme. There were bells, mistletoes and cute lightning everywhere, especially in the shopping street, Strøget. In this specific street there were all kinds of shops, and many of them do not exist in Norway like Topshop, and Abercrombie so I was extremely happy about that.
For those of you that are not that interested in shopping, take a trip on the paris wheel, in their super nice tivoli. Try out caramelized apples, and enjoy your time. There is also very pretty decorations at the tivoli, so bring your camera!
If you have money, and time there is an aquarium a cab drive away from centrum. At the aquarium it was a tunnel, so you got the opportunity to walk under where sharks, and other cool fish swam. That was quite a memorable experience, and I highly recommend it. The aquarium were located at the coast, and Denmark is well-known of its coastline, so then you can get a glimpse at that too!
Biking is also super easy because Denmark is so flat. In other words, easy to explore the city. There were bikes for rent outside our hotel, and the rent was cheap and really easy to do if you have a smartphone. We stayed at Grand Hotel, which sounds really luxury, but it is luxury for a small amount of money! I believe we stayed there for 850 NOK, which is approximately 90$-ish. For a long-weekend it´s a really fair price I think, it was included breakfast!