Hello, my recommendation is to look for a place to stay in Badalona. It only takes about 15 min from the train station in Badalona to get to Plaça Catalunya in Barcelona and only about 8 min from Badalona to metro station Clot. The train uses the exact same trip ticket needed for the metro and bus system in Barcelona. The trains pass just as often if not more often than the metro.

http://www.aj-badalona.es/
http://www.badalona.minorisa.es/ajuntament/