Spending one day in Amsterdam is a very short time to be able to do everything. But in my opinion, it is better to leave with a few good memories than to try to fit everything in a busy schedule and not be able to relax and enjoy your time :-)
We left Belgium and drove to Amsterdam in early morning, and left our car in a “park & ride” parking, the cheapest option when you go by car in this city (free public transport to the city centre is included in the price).
We decided to spend most of our day wandering along the canals, passing in front of Ann Franck House and other interesting buildings. We sat down at a little café around lunchtime and play with mr kitty. In the afternoon, we came across a floating flower market, apparently called the Bloemenmarkt. It was interesting. After dinner in a Steak House, we wandered through the famous Red Light District in the early evening, to experience that part of the city.
The town is busy, no doubt, but if you go off the beaten paths, it is possible to enjoy the quietness of the town (visiting The lovely Begijnhof for example), and to relax a bit.