Family sites Belgium / Netherlands

[MrsC_vannerxx]

We are planning a short trip of 2 weeks in August as an introduction to Europe in our Beach. Kids are 10 and 8 have specifically asked to visit Belgium and Amsterdam. Would rather stay in a few larger sites with facilities (pool etc) than lots of overnight stops. Recommendations for such family friendly sites, particularly those with good access to pubic transport to surrounding cities/attractions would be very much appreciated, along with any other advice from those who have done similar. Many thanks