Check out this forum:

http://www.flyertalk.com/travel/fttr...ML/000018.html

By far the best deal going in AMS is booking a room at either the Renaissance or the Marriott through Priceline. People have gotten prices as low as $60 a night in those ***** hotels. The Renaissance is a 5 minutes walk from Centraal, the Marriott is the Museum district.

I ended up getting a deluxe room at the Renaissance at $90 a night on Priceline UK booking only 5 days in advance, after having a lower bid rejected on Priceline US. Do try the other service if your first bid is rejected.
FYI, Priceline paid $99 for my room according to the Marriott website.

If you are a Marriott Rewards member, you can even get credit at this rate and, if staying at the Renaissance, get the ongoing 1000 miles bonus on UA or DL if signed up for the miles options.