We can recommend the following hotels near the congress venue:
Amsterdam is very easy to reach by plane, train, car or even boat. The award-winning Amsterdam Airport Schiphol is centrally located and flies to 323 destinations. From Amsterdam, high-speed rail services connect Amsterdam to Paris, London, Berlin and Brussels, and the Port of Amsterdam ranks fourth in Europe.
Flight: Amsterdam Airport Schiphol (AMS) is a major intercontinental flight hub and the home of KLM, the national flag-carrying airline of the Netherlands. Travelers can reach Amsterdam Centraal train station in the city center by taking a 15 minute train trip from Schiphol airport for 5€.
Train: Amsterdam Centraal train station is centrally located, so it is easy to walk to many of the major attractions.
Bus: Alternatively, the Amsterdam Airport Express (Bus #197) departs every 15 minutes from platform B9 at Schiphol plaza. The bus also costs 5€ takes approximately 30 minutes to reach the city center. Both the bus and train are far cheaper that taking a taxi from the airport, which charges 45€ to reach the city center.
Find more information here on how to get to Amsterdam.