My wife and I stayed at the Hilton in Amsterdam for one night last week. It was a very nice place, but beware of its location, it is nowhere close to the center of Amsterdam. Although I believe it is technically in the city, it feels like a close by suburb.
They do treat Diamonds well, however. The executive club lounge was open all day with full breakfast, very light snacks during the day and a full bar (gratis) at night with some mediocre apps. The best part is access to good coffee (even decaf) and bottled water all day.
The room was very nice though we spent very little time in it. They did give us 2 single beds for some reason, but that may be because we checked in at 9AM and would have taken anything.
Do note the location, however. You can walk to the center of Amsterdam in something like an hour. We like to walk, so that wasn’t a problem for us, but I could imagine it would be for others. It is a few blocks from a few tram lines that will get you where you want to go pretty efficiently. It is also about a 20 minute walk from the city’s south train station, so make sure to get off at the south station if you are taking the train from the airport. The central station is too far away.
Amsterdam, Netherlands 1077 BG