Just bear in mind that city break prices don't follow the trends of beach resorts. Hotel prices in popular cities like Barcelona can rocket during local holidays - like Easter - 200 -300% isn't impossible. But, on the other hand, they may be a bit cheaper in the school holiday periods when business travel demand is low. And flight only fares can do the same. Lisbon would be a good one to play with the dates on, there's probably a dip in prices in August compared to July because so much of the hotel trade and scheduled airlines will normally depend on business and government travel.

Thanks Steve, will keep that in mind .

In 2012 I could only realistically do easter holidays, or end of september, so quite fixed on dates.

If you are in Barcelona over Easter they will be playing Getafe at home on the 11th of April.
Tickets can easily be purchased online, and are now available for that game from their official website fcbarcalona.com

Keep your valuables safe when in the city, especially when on public transport.
Be wary of people that approach you either trying to sell stuff or asking for directions.

Barcelona is often described as a beautiful place full of nasty people. It is not a safe city.