I happen to think AMS is a fine hotel city. I think IC Amstel, Conservatorium, The Grand, De l'Europe, and the Waldorf (despite the blasé nature of ANY WA's rooms, in any city) are all more than competent options - maybe not 5*+, but 5* IMO.

Add in the 4*s (Pulitzer, for example) and you have a lot to work with.

It's luxury in the minimalist/Japanese style, not sure it's exactly 5*, but Hotel Okura looks very nice. Ate at Yamazato (1 Michelin star) in lobby and was uber impressed. More a business area, though.