LUX...it's pretty enough and has some decent restaurants, but there's not much to see and everything (food, drink, hotels) is really expensive: personally, wouldn't be my choice for a weekend break, other than at most for one night to see the old town, hang out in a few cafes etc...
It's at least a very easy and efficient airport and a quick bus ride into town, so avoids some of the schlepping about that can make a short weekend away painful at times