If you would like to experience Holland, I would advise against Duinrell, it really is a resort type campsite. It could be anwyhere. As said by another poster, Geldrrland and Friesland are really picturesque and I would much rather camp there than in Den Haag, Amsterdam or Rotterdam. Other places could include Zeeland ( if you like a beach type holiday) or Limburg ( the South Eastern tip of the Netherlands, which is not as flat, usually has the best weather in summer and has got Maastricht, a really nice city to shop and eat in)