Why yes I do have some recommendations. Ahem. First, for seafood, a good meal can be had at Rey de la Gamba, which is in Barceloneta along the port side. Don't be suckered into a different restaurant along the way...
Traditional Catalan country food is good at Julivert Miu which is off the Ramblas on C/Bonsuccés (near Pl. Cataluña), I recommend this place strongly. It has a great ambience and food is simple and good. Get a surtido or two, pan con tomate, a bottle of tinto, and you're set. Facing towards the port, C/Bonsuccés is the second street on the right if one walks down las Ramblas. The restaurant is on the left a short way down.
La Fonda, C/Escudellers 10, is decent but good luck getting a table. This street is on the left towards the lower end of las Ramblas. Yes the cruddy part.