Time for a road trip.
Quick metro ride over to the local Hertz, picked up a surprisingly nice little Volvo V40 D2 hatchback (why don't we get this in the USA again? The V50 is a lame duck compared to its V40 sibling), some hellish fun navigating Barcelona roads, and finally a time to blast (slowly) the mountain highways to Andorra.
The mountain towns are quaint collections of brick and stone punctuated by very modern rest stops, some very easy border crossings (Spain to Andorra, Andorra to France, France to Spain), and once deep into Andorra, some pretty good looking ski resorts. Sadly we didn't have time to hit the slopes...
Andorra has a reputation as a shopping paradise for Western Europeans, and perhaps to them it is, but we were mostly unimpressed-- except for the alcohol prices, which were very affordable. Sadly the hassle transporting a liter or two of scotch didn't seem worth it, as tempting as it was. Much more important was the drive and the experience of another new country, which was well worth the time. Even if you don't shop, a visit in the winter to go skiing/snowboarding (and, perhaps, so the rest of the party can go shopping) is worth it. Just don't expect much from the dining options (at least not that we could afford...).
A little over 9 hours of driving time and just under 500 miles later, we were back in Barcelona (diesel FTW, 44.3mpg!). A quick stop by La Rambla and a mostly-closed-for-the-night La Boqueria, some (best described as "interesting") Japanese food at a place called Udon (noodle sushi?), and some truly awful churros con chocolate right on La Rambla... then it was time to re-stock on iberico ham-flavored potato chips (Ruffles and Pringles, genius move!) and conclude what was a very good day.