The best thing about Amsterdam is the adventure. Go away from the center and you will meet wonderful people. Or go to Duivel the rap club and you will surely meet nice people
Just walk it. Get lost in the side streets. Try all the pastries. The airport has the city train running under it and baggage storage. Even if you are only laying over for a little bit - get out of the airport and check it out
Walking around at night, eating pommes, checking out the red light district, and visiting the Rijksmusem and Rembrandtplein was magical and I felt safe, even as a woman, alone.
Lovely city, beautiful canals and streets. Great museums, lovely food! Not just a crazy nightlife, lots of other things to do. But it does have a great nightlife if you want it!