There's no Sheraton hotel in the city, only the airport hotel, which is a 20 mins. train ride to the Central Station.

The only SPG option in the city center would be the Pulitzer.

With IHG you have a few more options. Besides the Intercontinental Amstel there is a Crowne Plaza in the city center which can still be booked for 35K points (by phone, until 18 March) and there are a few properties a bit farther out at 25K each (by phone, until 18 March), of which the new CP Amsterdam South consistently gets excellent reviews on Tripadvisor (15 mins. to city by public transportation).

The Pulitzer and the Amstel are both excellent 5* hotels. Can't comment on SPG as I am not a member, but for IHG the Amstel @ 40K points is definitely the best option location-wise and from a value-for-points perspective.

If you want to save some points and do not necessarily need to stay in the city center then you may want to consider the CP South @ 25K points.