Copenhagen is perfect for a citytrip. The city is lively and there is always something to see, in particular if you are a lover of gastronomy, design or shopping. Every district has its own unique character. Because of the rich history of the city there is also a variety of art and architecture to admire. Copenhagen is pretty small which lets you explore the city in a short amount of time. Especially when you rent a bike which you can do for around ten euros.
Even though Copenhagen is affiliated with the EU, you have to pay with Danish Crowns instead of Euros. In general, prices are comparable with Dutch prices, altough you have to keep in mind that drinks are a little more expensive.