I thought a couple of words about where to stay and what kind of accommodation you should be looking at was a little overdue. With regard to location I do suggest that you do look at somewhere within walking distance of the Ramblas. realistically it is in this area you’ll be spending most of your time. If you do see something a little way out then don’t fret, the public transport system here is cheap, convenient and largely, overwhelming smell of pish free. The other thing you’ll notice is that taxis are comparatively cheap. If you are staying in central Barcelona you’d be paying 10 euro at most for a trip home from the Ramblas area.
As far as the type of accommodation goes then my advice is this, be realistic about what you plan to do during your visit and who you are coming with.
A group of blokes and girls here for a party weekend are wasting money on a good hotel, realistically you will only be using the room to clean vomit off yourself and slipping into a coma on the bathroom floor.
For a civilised visit then I would suggest that you look at the Hotel Banys Orientals, it’s a great hotel, great location and the feedback I’ve had about it is uniformly first rate.
The other option, and one that is becoming really popular is looking at apartments. If I was planning a visit this is definitely the way I’d go. Having basic kitchen facilities i.e a beer fridge is tempting. If there are a few of you coming then you will find that there are some great apartments available and if the cost is split between 4 or 6 people it makes the trip very affordable.
Here are a couple of links that can point you in the right direction for finding the best accommodation for your stay.
Good site for finding hotel deals