Outside Barcelona (2)
The Costa Dorada
South of Barcelona is the Costa
Dorada. Easy to get to by train is the lovely seaside town of Sitges (site not currently available in English) - lovely at least on a
sunny mid-winter weekday, that is, when it's not packed with tourists.
Has information on what to see in both in Barcelona and on the Costa Dorada, to the south - Tarragona, La Pineda, Salou, Cambrils and Reus, as well as a considerable number of small, interesting towns inland.
Well to the south of Barcelona, there is the remarkable Ebro delta, remarkable for its bird life, for which you will need either a car or else a train and a bicycle.
The Costa Brava
If you are going to hire a car, I'd strongly recommend the Costa Brava, again particularly outside the tourist season. Tossa de Mar and Sant Feliu de Guixols are two small towns remarkably unspoilt by tourism, with Cadaqués being the place you'll find recommended in all the guidebooks.
If you are interested in Dalí, you have three Dalí museums on the Costa Brava, the most important of which is inland at Figueras.
Inland from Barcelona
Easily accessible by train you have the spectacularly located monastery at Montserrat which you can get to by cable car or mountain railway (the latter being recommended if you've got zero head for heights).
Further afield, if you want to see some mountains, there's the equally lovely Vall de Nuria, which you can also (only) get to by train and mountain railway, though you might want to consider an overnight stay to get the most out of it. In the winter, you will find it is crowded with skiers.
With a car, without venturing too far outside the city, the regions of the Montseny and the towns of Besalú and Banyoles also for a nice day out. For a weekend away, the Vall d'Aran is a 4-hour, 350 km drive but well worth it. The National Park of Aigüestortes i Estany de Sant Maurici is closer but still a longish drive, but a fantastic place for some strenuous hiking.
Online you will find information in English on Catalonia's gorgeous natural parks.
For the energetic, Catalonia also has a remarkable network of local and long distance footpaths (information only in Catalan).