* The Mediterranean climate means that Barcelona is rarely uncomfortably cold, even in winter. It can though be very hot and humid in the summertime. Early summer and autumn are the ideal times to visit, especially May to June and September to October. In winter, days are crisp but often sunny and snow is rare. Most rainfall is in April. We found this to be true during our visit. It rained a couple of days, but actually did not feel unpleasant as the temperatures were still warm. July and August are very hot and humid - even at night. We visited in the past in July and had rainfall then too, so you never know. It does work though year around as a family break destination. If you do schedule your trip for the summer you can take advantage of the city's 4 golden sandy beaches. We did manage to spend one afternoon on the beach in April too!
* Buy reminders of all the Gaudi artwork you see everywhere in Barcelona. There are mosaics, tiles and miniature mosaic houses and Gaudi dragons - they all make good souvenirs.
* Look out for the Gaudi pavements all over the city. The pavements have Gaudi designs on them that he used on the floors in his houses. On the Passeig de Gracia, look out for hexagonal shapes with sea motifs. In other parts of the city, keep your eyes peeled for square pavement tiles with flower designs. On the Ramblas there are wavy patterns everywhere.
* Barcelona is very child friendly and every establishment we went to was pleased to see children. They do not tend to serve their evening meals until 9pm or sometimes even later, so it is actually good to be like locals and have a siesta after lunch. Most of the touristy restaurants though, do serve food all day.
* Apparently Barcelona is one of Europe's pick pocketing capitals. We had no problems, but you do need to be alert in crowded places like the train stations and the Ramblas. The subway is said to be a hotbed for pick pocketing activity and they have films showing down there warning you to beware. Apparently it can range from simple opportunistic thefts to co-ordinated attacks. The platform at Sants train station and the one at Sagrada Familia are places where you are warned to be especially careful. Hold on to your bag at all times and never leave anything unattended while you are in a cafe. We had a drink in one place off the Ramblas, the lady working there warned us to keep our camera close, apparently 2 bags had been stolen earlier that day! Beware of anone trying to touch you and only carry the cash you need, never your passport. Keep a close eye on your camera and never put it on the table in front of you in a cafe. Violent crime is uncommon, and we had no problems whatsoever, but you just need to be alert and careful.