We have blocked rooms in three hotels which can be booked
via this site (this site closes March 21st.) The Tropen Hotel is
in-between the CWI (1st day venue) and the Trippenhuis (venue for day
2 and 3.) The Carlton and City Centre hotel are within walking
distance (550m and 850m) from the Trippenhuis.
There are many smaller and less expensive hotels that can be checked
out via a booking page like this one.
(don't forget to check the rates on the page of the hotel directly before
booking via such a site.)
A cheap option is to stay in one of the
three stayokay hostels in
Amsterdam (they do have private rooms.) All three are within biking
distance to the venues. The A'dam Stadsdoelen hostel is very close to
the Trippenhuis, the A'dam Zeeburg is closer to CWI.