I stayed at the de Witt in August and likely will again in November.
Very clean and comfortable. Had only opened this year after a huge refurbishment.
Also very 'American' in that when I was there there were a few US tour parties (all with their 'hi my name is ...' labels and lanyards and plastic pouches hanging around their necks) and the bar and restaurent seemed to be more US orientated than Dutch but very high quality.
Good location approx 5 mins from Centraal Station.