We loved Holland. Went last year. Our kids are smaller though, and we generally like smaller quieter sites. I would particularly recommend Texel though - sure there were large sites by the sea with lots to do. Beautiful island with awesome beaches and cycle tracks everywhere.
Maybe take a look at Camping Zeeburg (outskirts of Amsterdam). It's a big, lively site and has a tram close by which takes you into the centre of Amsterdam in minutes (we used the Park and Ride at Zeeburg and only paid about 8 euros for return travel for five of us into the centre).