Just stayed there over New Years...I am Diamond and was upgraded to concierge level....I have to warn you though...the room was smaaallll...I had a friend of mine with me and we were pretty tight in there. Nice hotel but as the poster above said....a little out of the way.....it's about a 10 minute walk to the nearest tram stop....there are 2 to choose from..I forget the numbers. If you're going to be out late...the tram stops running at an early hour...so you'll need to cab it back.
You should do a search on attractions in AMS.....it's very heavily discussed.