Visiting friends is one of my favorite excuses to choose travel destinations. It is nice as you get to see people who are normally a bit far away, you have local guides to show you the city, and you can actually see another city.
You can see in the pictures, there is a lot of light, and that is relative uncommon when you go to the north of Europe, and that could be felt in everyone there. People were happy, and channels looked like a busy road in Madrid on a workday, but instead of cars, there were hundreds of boats.
The channels make Amsterdam one of the nicest cities in Europe that I know, and the fact that it is completely flat, and bikes are the most extended mean of transportation for everybody, create a calm atmosphere difficult to beat.