Although they're such small places, Belgium, Holland, and Luxembourg contain a diversity of culture, language, and tradition that defies easy definition. This is true even within each individual country.
Belgium, for example, is fractured along the age-old European great divide between the Germanic north and the Latin south, a division expressed in the constant regional bickering between Dutch-speaking Flanders and French-speaking Wallonia that threatens to split the country entirely. There's even a small community of German speakers in the east who, repeatedly displaced by successive wars, have been bouncing back and forth between Belgium and Germany and wryly call themselves "the best Belgians of all."
Holland (the Netherlands) also has its great divide, along the "three great rivers"--the Maas, the Waal, and the Rhine (incidentally, the Dutch show just what they think of Germany's great river by changing its name to the Lek on their territory). The northerners are straitlaced and Calvinist and only know what to do with a glass of beer because they've been shown by the exuberant, Catholic southerners. Then there's the matter of nations within the nation. Not even the Romans or Charlemagne could do much with independent-minded Friesland, so the bureaucrats in The Hague don't stand a chance. Zeeland and Limburg also have their notions of separateness and, like Friesland, their own languages to back them up.
And as for Luxembourg, you'd think a country so small that even on a big map its name can't fit within its borders would be simpler. Not a bit of it. Luxembourgers are such a mixed bag that they're still trying to sort out the mess left behind when the Germanic tribes overran the Roman Empire's Rhine defenses in A.D. 406.
Benelux came into existence in 1944 as much as anything because these small countries were tired of being trampled by bigger neighbors with sharp elbows and puffed-out chests. It was the seed from which the subsequent European Coal & Steel Community, then the European Economic Community, then the European Community, and finally the European Union, emerged.
The Benelux nations' diversity is their greatest asset, culturally and in terms of tourism. Their willingness to adapt diversity to the needs of a new era is perhaps their best gift to the new Europe. The visitor from afar may well be more impressed by their shared characteristics, which include a determined grasp on the good life, than by the differences that separate them.