Belgians have the best french fries and beer.
Bruges is nearby and though it is a little touristy during a day (particularly a weekend), if you head down the back alleys there are good bars, good views, and you can get Westvleteren 12.
I thought Brussels sucked. If you really like the Flemish masters, their museum has some good stuff, but I think it's better to skip.
If you like champagne, it's an hour bullet train to Reims, which has a number of champagne houses (and an amazing cathedral). If you can drive stick, there are more boutique champagne places and WWI sites right around Reims, and it's much cheaper than Paris.
I second Bruges, love that little town (and they have one of the off-the-radar football clubs I follow). Brussels is so-so, though I do enjoy in the warmer months lounging around Grad-Place in the evening and seeing how far I can make it through one of the pub's exhaustive beer menus.
On the Dutch side, Amsterdam is fun and has some great museums; but, a bit touristy. Can easily swing a day trip to Haarlem or if its warm, the beaches around Zandvort from there. I have not been there; but, I have a friend who really like Rotterdamn as a 'true' Dutch city. Of course, you can always grab a bike and zip around most fo the country on two-wheels.
Back over the France, Paris is Paris. Great museums, culture, and food (though expensive); but, overwhelmed at times by tourists and the underwhelmed by the less than friendly Parisians. Its a lot better if you know some French and are not afraid to go off the beaten path as the Metro makes it easy to get to and the heart of Paris is in the neighborhoods, like the old guy in the 7th arr. my wife and I found on our honeymoon off of a side street that made the best crepes from his little cart I have ever had to date (the guy was actually reviewed by the NY Times) or the family run, tiny, 4-Star Michelin restaurant we stumbled across in the back-end of the Latin Quarter whose menu was only in French where the food was amazing while siting next to another couple, one of whom was a Brit that studied in the same city I did in France. Outside of Paris, Versailles is an easy half-day trip on the RER while
Chartres, Reims and Rouen ae accessaible by train for day trips. The one area I have not been to yet and need to get to is Normandy (my Grandfather landed at Utah beach on D-Day), which is a quick train ride from Paris; but, one needs more than one day there.
