I have stayed in a suite and single room at the Ambassade (E325 for suite and E185 for single). Both had "queen" bed that was two twins pushed together. Stayed at the Prins Hendrik - E200 with all twin beds pushed together. I have also stayed at the Marriott E260 that had a wonderful KING (and I mean US "Real" King!!) bed! Good luck. Perhaps you can get a better rate since it is later in the year (Sept is very busy in A'dam)