Lloret de Mar
I spent a few days in Lloret de Mar, in December, a few years ago. We found a “super-extra-cheap” hotel offer (at this time we were living in Madrid). The town was nearly dead, only groups of elderly Spaniards (dancing all the time) and a bunch of young Brits (drunk all the time, so probably they will not need more :-)
Can't remember the name of the hotel. Never mind, it was quite ugly. The weather was very cold and windy...
At this point, you may think we had a miserable time.... Not at all!! It was perfect to discover the little medieval towns inland (Besalú, Ripoll, Pals...), the volcanic area of Olot, Cadaques without the crowds, the archeologic site of Ampuries, the Jewish quarter of Girona, enjoying one sunny morning in a desert beach... (but if you're looking for party, winter it's definitely not the right time)
Later, after moving to Barcelona, I did not have any intention to visit Lloret again (there are so many better towns and sights around). But there are a few off-the-way possibilities if you want to explore a little... see my tips below!