To be honest, I am not a fan of Raval. I usually feel a bit uncomfortable and unsafe especially at night in Raval. I think during day time, it is OK but you still need to watch out your belongings. Actually, it is true for all parts of Barcelona :)
When we have some friends visiting Barcelona, we usually meet in the down town and Raval is a good option to have some drinks as around La Rambla is too touristic and overpriced.
Joaquin Costa Street is full of bars and we found this cosy bar when we were looking for a place where we can talk without needing to shout and have a drink.
Apart from having a relaxed atmosphere with walls full of books, Lletraferit has lots of choices for drinks like teas, infusions, cocktails, gin tonics and of course beers.
Address: Carrer de Joaquin Costa 43
Metro: L2 – Universitat, L3 – Plaza Catalunya
Caña : 1€
Gin Tonics: 7€ – 9€