There are many accomodations nearby the congress venues. The three hotels closest to Pakhuis de Zwijger are, all within 10 minutes of walking:
Hotel Jakarta Amsterdam by Westcord
Mövenpick Hotel Amsterdam City Centre
Pension Homeland
An interactive map displaying all hotels in the area of Pakhuis de Zwijger can be found here.
An interactive map displaying all hotels in the area of the Concertgebouw can be found here.