The Okura is exquisite and if you can swing it thats my recomendation. Its also a quick walk to the venue so no cab fares or buses. But as stated its a little pricey, but everything Amsterdam especially during Queens Day, is.
Prices are sky high as queensday is maybe the most expensive day to get a hotel in amsterdam all year long. Lucky if u find a decent one.. I think most are full already.
Besides that ur lucky enough if u even can GET to the hotel as most trams dont ride, buses dont and its so crowded it takes you hours to get trough.