Hola!
I traveled to BCN in December last year, and stayed at the Hostal Opera. It was really close to the northern part of the Rambla, very clean and safe. Site at
www.hostalopera.com Price was 58 Euros for a double with bath, if I remember correctly.
Actually I posted a trip report on this forum. I do not know, how to link that into this reply (the nerd that I am when in comes to computers), but you should find it, if you search for "Barcelona trip report" in the forum.
It was my first trip to BCN, and I have been told, that you should avoid the El Raval quarter at night.
It is a gorgeous city, enjoy your trip! Feel free to contact me for further questions!
From Prussia with Love,
la calma